KR102371670B1 - Bit interleaver for 16-symbol mapping and low density parity check codeword with 16200 length, 2/15 rate, and method using the same - Google Patents

Abstract

A bit interleaver, a BICM device, and a bit interleaving method are disclosed. A bit interleaver according to an embodiment of the present invention includes: a first memory for storing an LDPC codeword having a length of 16200 and a code rate of 2/15; a processor for generating an interleaved codeword by interleaving the LDPC codeword in units of bit groups having a size corresponding to a parallel factor of the LDPC codeword; and a second memory that provides the interleaved codeword as a modulator for 16-symbol mapping.

Description

A bit interleaver for LDPC codeword with a length of 16200 and a code rate of 2/15 and 16-symbol mapping and a bit interleaving method using the same {BIT INTERLEAVER FOR 16-SYMBOL MAPPING AND LOW DENSITY PARITY CHECK CODEWORD WITH 16200 LENGTH, 2/ 15 RATE, AND METHOD USING THE SAME}

The present invention relates to an interleaver, and more particularly, to a bit interleaver for dispersing a burst error occurring in a digital broadcasting channel.

BICM (Bit-Interleaved Coded Modulation) is a bandwidth-efficient transmission technology that includes an error-correction coder, a bit-by-bit interleaver, and a high-order modulator. It is a combined form.

BICM can provide excellent performance with a simple structure by using a low-density parity check (LDPC) encoder or a turbo encoder as an error correction encoder. In addition, the BICM provides a high level of flexibility because a modulation order, a length of an error correction code, and a code rate can be variously selected. Because of these advantages, BICM is highly likely to be used not only in broadcasting standards such as DVB-T2 and DVB-NGH, but also in other next-generation broadcasting systems.

Despite these advantages, if the BICM does not properly distribute burst errors generated in the channel through the bit-by-bit interleaver, the performance of the BICM is rapidly deteriorated. Therefore, the bit-unit interleaver used in BICM should be designed to be optimized for the modulation order, the length of the error correction code, and the code rate.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a bit interleaver in a BICM capable of effectively distributing burst errors occurring in a broadcasting system channel.

In addition, it is an object of the present invention to provide a bit interleaver that is optimized for an LDPC encoder having a length of 16200 and a code rate of 2/15 and a modulator performing 16-symbol mapping and applied to a next-generation broadcasting system such as ATSC 3.0. will do

According to an aspect of the present invention, there is provided a bit interleaver comprising: a first memory for storing an LDPC codeword having a length of 16200 and a code rate of 2/15; a processor for generating an interleaved codeword by interleaving the LDPC codeword in units of bit groups having a size corresponding to a parallel factor of the LDPC codeword; and a second memory that provides the interleaved codeword as a modulator for 16-symbol mapping.

In this case, the 16-symbol mapping may be a NUC (Non-Uniform Constellation) symbol mapping having 16 constellations.

In this case, the parallel factor is 360, and the bit group may include 360 bits.

(N _ldpc 는 16200)와 같이 표현되고, 하기 수학식 9와 같이 각각 360개의 비트들로 구성된 45개의 비트그룹들로 분할될 수 있다.In this case, the LDPC codeword is

( N _ldpc is 16200), and can be divided into 45 bit groups each consisting of 360 bits as shown in Equation 9 below.

[Equation 9]

( X _j is the jth bit group, N _ldpc is 16200, N _group is 45)

In this case, interleaving may be performed using Equation 10 below using a permutation order.

[Equation 10]

( X _j is the j-th bit group, Y _j is the interleaved j-th bit group, and π( j ) is the permutation order for interleaving per bit group)

In this case, the permutation order may correspond to the interleaving sequence expressed by Equation 11 below.

[Equation 11]

interleaved sequence

={5 33 18 8 29 10 21 14 30 26 11 23 27 4 7 6 24 44 38 31 34 43 13 0 15 42 17 2 20 12 40 39 35 32 1 3 41 37 9 25 19 22 16 28 36}

In addition, the bit interleaving method according to the present invention comprises the steps of: storing an LDPC codeword having a length of 16200 and a code rate of 2/15; generating an interleaved codeword by interleaving the LDPC codeword in units of bit groups having a size corresponding to a parallel factor of the LDPC codeword; and outputting the interleaved codeword to a modulator for 16-symbol mapping.

In addition, the BICM apparatus according to the present invention includes an error correction encoder for outputting an LDPC codeword having a length of 16200 and a code rate of 2/15; a bit interleaver for outputting an interleaved codeword by interleaving the LDPC codeword in units of bit groups having a size corresponding to a parallel factor of the LDPC codeword; and a modulator for 16-symbol mapping the interleaved codeword.

According to the present invention, there is provided a bit interleaver in a BICM capable of effectively distributing burst errors occurring in a broadcasting system channel.

In addition, the present invention provides a bit interleaver that is optimized for an LDPC encoder having a length of 16200 and a code rate of 2/15 and a modulator performing 16-symbol mapping to be applied to a next-generation broadcasting system such as ATSC 3.0.

1 is a block diagram illustrating a broadcast signal transmission/reception system according to an embodiment of the present invention.
2 is an operation flowchart illustrating a broadcast signal transmission/reception method according to an embodiment of the present invention.
3 is a diagram illustrating a structure of a parity check matrix corresponding to an LDPC code according to an embodiment of the present invention.
4 is a diagram illustrating bit groups of an LDPC codeword having a length of 64800.
5 is a diagram illustrating bit groups of an LDPC codeword having a length of 16200.
6 is a diagram illustrating interleaving in units of bit groups according to an interleaving sequence.
7 is a block diagram illustrating a bit interleaver according to an embodiment of the present invention.
8 is an operation flowchart illustrating a bit interleaving method according to an embodiment of the present invention.

The present invention will be described in detail with reference to the accompanying drawings as follows. Here, repeated descriptions, well-known functions that may unnecessarily obscure the gist of the present invention, and detailed descriptions of configurations will be omitted. The embodiments of the present invention are provided in order to more completely explain the present invention to those of ordinary skill in the art. Accordingly, the shapes and sizes of elements in the drawings may be exaggerated for clearer description.

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

1 is a block diagram illustrating a broadcast signal transmission/reception system according to an embodiment of the present invention.

Referring to FIG. 1 , it can be seen that the BICM device 10 and the BICM receiving device 30 communicate via the wireless channel 20 .

The BICM device 10 encodes k-bit information bits 11 in the error correction encoder 13 to generate an n-bit codeword. In this case, the error correction encoder 13 may be an LDPC encoder or a turbo encoder.

The codeword is interleaved by the bit interleaver 14 to generate an interleaved codeword.

In this case, interleaving may be performed in units of bit groups. In this case, the error correction encoder 13 may be an LDPC encoder having a length of 16200 and a code rate of 2/15, a codeword having a length of 16200 may be divided into a total of 45 bit groups, and each of the bit groups is an LDPC encoder. It may include 360 bits that are parallel factors of the codeword.

In this case, interleaving may be performed in units of bit groups corresponding to an interleaving sequence to be described later.

In this case, the bit interleaver 14 effectively disperses clustering errors generated in the channel to prevent performance degradation of the error correction code. In this case, the bit interleaver 14 may be individually designed according to the length and code rate of the error correction code and the modulation order.

The interleaved codeword is modulated by the modulator 15 and transmitted through the antenna 17 .

In this case, the modulator 15 is a concept including a symbol mapping device. In this case, the modulator 15 may be a symbol mapping device that performs 16-symbol mapping in which codes are mapped to 16 constellations.

In this case, the modulator 15 may be a uniform modulator, such as a Quadrature Amplitude Modulation (QAM) modulator, or a non-uniform modulator.

In particular, the modulator 15 may be a symbol mapping device that performs non-uniform constellation (NUC) symbol mapping having 16 constellations.

A signal transmitted through the radio channel 20 is received through the antenna 31 of the BICM receiving device 30 , and the BICM receiving device 30 undergoes a reverse process of the process that occurred in the BICM device 10 . That is, the received data may be demodulated by the demodulator 33 , deinterleaved by the bit deinterleaver 34 , and then decoded by the error correction decoder 35 to finally recover information bits.

It is apparent to those skilled in the art that, in addition to the above-described transmission/reception process being described within the minimum range necessary to describe the characteristics of the present invention, many processes necessary for data transmission may be added.

2 is an operation flowchart illustrating a broadcast signal transmission/reception method according to an embodiment of the present invention.

Referring to FIG. 2 , in the method for transmitting/receiving a broadcast signal according to an embodiment of the present invention, first, information bits are error-corrected and encoded ( S210 ).

That is, in step S210, k-bit information bits are encoded by an error correction encoder to generate an n-bit codeword.

In this case, step S210 may be performed like an LDPC encoding method to be described later.

Also, in the broadcast signal transmission/reception method, an interleaved codeword is generated by interleaving an n-bit codeword in units of bit groups (S220).

In this case, the n-bit codeword may be an LDPC codeword having a length of 16200 and a code rate of 2/15, and a codeword having a length of 16200 may be divided into a total of 45 bit groups, and each of the bit groups is an LDPC codeword. It may include 360 bits corresponding to a parallel factor of .

In this case, interleaving may be performed in units of bit groups corresponding to an interleaving sequence to be described later.

In addition, the broadcast signal transmission/reception method modulates the encoded data (S230).

That is, in step S230, the interleaved codeword is modulated by a modulator.

In this case, the modulator is a concept including a symbol mapping device. In this case, the modulator may be a symbol mapping device that performs 16-symbol mapping in which codes are mapped to 16 constellations.

In this case, the modulator may be a uniform modulator, such as a Quadrature Amplitude Modulation (QAM) modulator, or a non-uniform modulator.

In particular, the modulator may be a symbol mapping apparatus that performs non-uniform constellation (NUC) symbol mapping having 16 constellations.

In addition, the broadcast signal transmission/reception method transmits modulated data (S240).

That is, in step S240, the modulated codeword is transmitted through an antenna through a radio channel.

In addition, the broadcast signal transmission/reception method demodulates the received data (S250).

That is, in step S250, a signal transmitted through a radio channel is received through an antenna of a receiver, and the received data is demodulated by a demodulator.

In addition, in the broadcast signal transmission/reception method, demodulated data is deinterleaved ( S260 ). In this case, the deinterleaving of step S260 may correspond to the reverse process of step S220.

In addition, in the broadcast signal transmission/reception method, the deinterleaved codeword is error-corrected and decoded (S270).

That is, in step S270, error correction decoding is performed through an error correction decoder of the receiver to finally restore information bits.

In this case, step S270 may correspond to the reverse process of the LDPC encoding method, which will be described later.

The LDPC (Low Density Parity Check) code is known as a code close to the Shannon limit in the AWGN (Additive White Gaussian Noise) channel, and has asymptotically superior performance than the turbo code, parallel decoding, etc. has the advantage of

In general, the LDPC code is defined by a randomly generated low density PCM (parity check matrix). However, the randomly generated LDPC code not only requires a lot of memory to store the PCM, but also takes a lot of time to access the memory. To solve this problem, a quasi-cyclic LDPC (QC-LDPC) code has been proposed, and the QC-LDPC code composed of a zero matrix or CPM (Circulant Permutation Matrix) is expressed by It is defined by the PCM represented by 1.

[Equation 1]

Here, J is a CPM having a size of L x L and is given by Equation 2 below. Hereinafter, L may be 360.

[Equation 2]

Also, J ⁱ is an L x L identity matrix I(=J ⁰ ) shifted to the right i(0=i<L) times, and J ^∞ is an L x L zero matrix. Therefore, in the QC-LDPC code, since only the exponent i needs to be stored to store J ⁱ , the memory required to store the PCM is greatly reduced.

3 is a diagram illustrating a structure of a parity check matrix corresponding to an LDPC code according to an embodiment of the present invention.

Referring to FIG. 3 , the sizes of matrices A and C are g x K and (N-K-g) x (K+g), respectively, and are composed of a zero matrix having a size of L x L and a CPM. Also, matrix z is a zero matrix of size gx (NKg), matrix D is an identity matrix of size (NKg) x (NKg), and matrix B is a dual diagonal matrix of size gxg matrix). In this case, the matrix B may be a matrix in which all elements other than the diagonal element and the elements adjacent to the bottom of the diagonal are all 0, or may be defined as in Equation 3 below.

[Equation 3]

Here, I _LxL is an identity matrix of size L x L.

That is, the matrix B may be a bit-wise double diagonal matrix or a block-wise double diagonal matrix using the identity matrix as a block as expressed in Equation 3 above. A general (bit-wise) double diagonal matrix is disclosed in detail in Korean Patent Application Laid-Open No. 2007-0058438 or the like.

In particular, when the matrix B is a normal (bit-wise) double diagonal matrix, row permutation or column permutation is applied to the PCM of the structure shown in FIG. 3 including the matrix B. It is apparent to those skilled in the art that conversion to quasi-cyclic is possible.

In this case, N is the length of a codeword, and K is the length of information.

In the present invention, as shown in Table 1 below, a newly designed QC-LDPC code having a code rate of 2/15 and a codeword length of 16200 is proposed. That is, an LDPC code that receives information having a length of 2160 and generates an LDPC codeword having a length of 16200 is proposed.

Table 1 shows the sizes of the A, B, C, D, and Z matrices of the QC-LDPC code of the present invention.

[Table 1]

The newly designed LDPC code may be expressed in the form of a sequence, the sequence and the matrix (parity bit check matrix) have an equivalent relationship, and the sequence may be expressed as shown in the table below.

[table]

Line 1: 2889 3122 3208 4324 5968 7241 13215

Line 2: 281 923 1077 5252 6099 10309 11114

Line 3: 727 2413 2676 6151 6796 8945 12528

Line 4: 2252 2322 3093 3329 8443 12170 13748

Line 5: 575 2489 2944 6577 8772 11253 11657

Line 6: 310 1461 2482 4643 4780 6936 11970

Line 7: 8691 9746 10794 13582

Line 8: 3717 6535 12470 12752

Line 9: 6011 6547 7020 11746

Line 10: 5309 6481 10244 13824

Line 11: 5327 8773 8824 13343

Line 12: 3506 3575 9915 13609

Line 13: 3393 7089 11048 12816

Line 14: 3651 4902 6118 12048

Line 15: 4210 10132 13375 13377

The LDPC code expressed in the form of a sequence is widely used in the DVB standard.

를 생성한다. 여기서, M₁=g, M₂=N-K-g이다. 또한, M₁은 이중 대각행렬(dual diagonal matrix) B에 대응하는 패러티(parity)의 크기이며, M₂는 항등행렬 D에 대응하는 패러티의 크기이다. 부호화 과정은 다음과 같다.According to an embodiment of the present invention, the LDPC code expressed in the form of a sequence is encoded as follows. Assume that an information block having an information size of K S=(s ₀ , s ₁ , ..., s _K-1 ). The LDPC encoder uses an information block S with a size of K to obtain a codeword with a size of N=K+M ₁ +M ₂

to create Here, M ₁ =g, M ₂ =NKg. In addition, M ₁ is the size of parity corresponding to the dual diagonal matrix B, and M ₂ is the size of the parity corresponding to the identity matrix D. The encoding process is as follows.

-Initialization:

[Equation 4]

를 상기 테이블의 수열의 제1행에 명시된 패러티 비트 주소들(parity bit addresses)에서 누적(accumulate)한다. 예를 들어, 길이가 16200이며, 부호율이 2/15인 LDPC 부호에서의 누적 과정은 다음과 같다.-First

is accumulated from the parity bit addresses specified in the first row of the numerical sequence of the table. For example, an accumulation process in an LDPC code having a length of 16200 and a code rate of 2/15 is as follows.

)은 GF(2)에서 일어난다.Add here (

) occurs in GF(2).

들에 대해서는, 하기 수학식 5에서 계산된 패러티 비트 주소들에서 누적한다.-The next L-1 information bits, i.e.

For , it is accumulated at the parity bit addresses calculated in Equation 5 below.

[Equation 5]

에 대응되는 패러티 비트 주소들, 즉 상기 테이블의 수열의 제1행에 표기된 패러티 비트 주소들을 나타내며, Q₁ = M₁/L, Q₂ = M₂/L, L = 360이다. 또한, Q₁과 Q₂는 하기 표 2에 정의된다. 예를 들어, 길이가 16200이며, 부호율이 2/15인 LDPC 부호는 M₁ = 3240, Q₁ = 9, M₂ = 10800, Q₂ = 30, L = 360이므로, 두 번째 비트

에 대해서는 상기 수학식 5를 이용하면 다음과 같은 연산이 수행된다.where x is the first bit

Parity bit addresses corresponding to , ie, parity bit addresses indicated in the first row of the sequence of the table, are Q ₁ = M ₁ /L, Q ₂ = M ₂ /L, L = 360. In addition, Q ₁ and Q ₂ are defined in Table 2 below. For example, an LDPC code with a length of 16200 and a code rate of 2/15 is M ₁ = 3240, Q ₁ = 9, M ₂ = 10800, Q ₂ = 30, L = 360, so the second bit

With respect to Equation 5 above, the following operation is performed.

Table 2 shows the sizes of M ₁ , M ₂ , Q ₁ , Q ₂ of the designed QC-LDPC code.

[Table 2]

부터

까지의 새로운 360개의 정보비트들은 상기 수열의 제2행을 이용하여, 상기 수학식 5로부터 패러티 비트 누적기들의 주소를 계산하고, 누적한다.-the next

from

For the new 360 information bits up to, the addresses of the parity bit accumulators are calculated from Equation (5) and accumulated using the second row of the sequence.

- In a similar way, for all groups composed of the new L information bits, the addresses of the parity bit accumulators are calculated and accumulated from Equation (5) by using the new row of the sequence.

에서

까지의 모든 정보비트들이 사용된 후, i = 1부터 시작하여 하기 수학식 6의 연산을 순차적으로 수행한다.-

at

After all the information bits up to are used, the operation of Equation 6 below is sequentially performed starting from i = 1.

[Equation 6]

- Next, when parity interleaving is performed as in Equation 7 below, parity generation corresponding to the double diagonal matrix B is completed.

[Equation 7]

)를 이용하여 이중 대각행렬 B에 대응하는 패러티 생성이 완료되면, M₁개의 생성된 패러티(

)을 이용하여, 항등행렬 D에 대응하는 패러티를 생성한다.K information bits (

) when parity generation corresponding to the double diagonal matrix B is completed, M ₁ generated parity (

) to generate a parity corresponding to the identity matrix D.

에서

까지의 L개의 비트들로 구성된 모든 그룹(group)들에 대해서, 상기 수열들의 새로운 행(이중 대각행렬 B에 대응하는 패러티를 생성할 때 이용한 마지막 행의 바로 다음 행부터 시작)과 상기 수학식 5를 이용하여 패러티 비트 누적기들의 주소를 계산하고, 관련 연산을 수행한다.-

at

For all groups consisting of L bits up to, a new row of the sequence (starting from the row immediately following the last row used to generate the parity corresponding to the double diagonal matrix B) and Equation 5 Calculate the addresses of the parity bit accumulators using , and perform related operations.

에서

까지의 모든 비트들이 사용된 후, 하기 수학식 8과 같은 패러티 인터리빙을 수행하면, 항등행렬 D에 대응하는 패러티 생성이 완료된다.-

at

After all bits up to are used, parity interleaving as shown in Equation (8) is performed, and parity generation corresponding to the identity matrix D is completed.

[Equation 8]

4 is a diagram illustrating bit groups of an LDPC codeword having a length of 64800.

Referring to FIG. 4 , it can be seen that an LDPC codeword having a length of 64800 is divided into 180 bit groups (0 ^th group to 179 ^th group).

In this case, 360 may be a parallel factor (PF) of the LDPC codeword. That is, since PF is 360, an LDPC codeword having a length of 64800 is divided into 180 bit groups as shown in FIG. 4, and each bit group includes 360 bits.

5 is a diagram illustrating bit groups of an LDPC codeword having a length of 16200.

Referring to FIG. 5 , it can be seen that an LDPC codeword having a length of 16200 is divided into 45 bit groups (0 ^th group to 44 ^th group).

In this case, 360 may be a parallel factor (PF) of the LDPC codeword. That is, since PF is 360, an LDPC codeword having a length of 16200 is divided into 45 bit groups as shown in FIG. 5, and each bit group includes 360 bits.

6 is a diagram illustrating interleaving in units of bit groups according to an interleaving sequence.

Referring to FIG. 6 , it can be seen that interleaving is performed by changing the order of bit groups according to the designed interleaving sequence.

For example, it is assumed that the interleaving sequence for an LDPC codeword having a length of 16200 is as follows.

Interleaving sequence = {24 34 15 11 2 28 17 25 5 38 19 13 6 39 1 14 33 37 29 12 42 31 30 32 36 40 26 35 44 4 16 8 20 43 21 7 0 18 23 3 10 41 9 27 22}

Then, the order of bit groups of the LDPC codeword as shown in FIG. 4 is changed as shown in FIG. 6 by the interleaving sequence.

That is, the LDPC codeword 610 and the interleaved codeword 620 each include 45 bit groups, and the LDPC codeword 620 in which the 24th bit group of the LDPC codeword 610 is interleaved by an interleaving sequence. is the 0th bit group, the 34th bit group of the LDPC codeword 610 becomes the 1st bit group of the interleaved LDPC codeword 620, and the 15th bit group of the LDPC codeword 610 is interleaved. The second bit group of the LDPC codeword 620 becomes the 11th bit group of the LDPC codeword 610 becomes the third bit group of the interleaved LDPC codeword 620, and the 2nd bit group of the LDPC codeword 610 is It can be seen that the th bit group becomes the 4 th bit group of the interleaved LDPC codeword 620 .

는 N _group = N _ldpc / 360 개의 비트그룹들로 쪼개어진다. 이 때, N _ldpc 는 16200일 수 있다. _LDPC codeword of length N ldpc

is divided into N _group = N _ldpc / 360 bit groups. In this case, N _ldpc may be 16200.

[Equation 9]

Here, X _j represents the j-th bit group, and each X _j consists of 360 bits.

The LDPC codewords divided into bit groups are interleaved as shown in Equation 10 below.

[Equation 10]

Here, Y _j represents an interleaved j-th bit group, and π( j ) is a permutation order for interleaving per bit group. The permutation order corresponds to the interleaving sequence of Equation 11 below.

[Equation 11]

interleaved sequence

={5 33 18 8 29 10 21 14 30 26 11 23 27 4 7 6 24 44 38 31 34 43 13 0 15 42 17 2 20 12 40 39 35 32 1 3 41 37 9 25 19 22 16 28 36}

That is, assuming that each of the codeword and the interleaved codeword includes 45 bitgroups from the 0th bitgroup to the 44th bitgroup, the interleaving sequence of Equation 11 is a codeword in which the 5th bitgroup of the codeword is interleaved. becomes the 0th bit group, the 33rd bit group of the codeword becomes the 1st bit group of the interleaved codeword, the 18th bit group of the codeword becomes the 2nd bit group of the interleaved codeword, and the codeword The 8th bit group of the interleaved codeword becomes the 3rd bit group, ..., the 28th bit group of the codeword becomes the 43rd bit group of the interleaved codeword, and the 36th bit group of the codeword becomes the This means that it becomes the 44th bit group of the interleaved codeword.

In particular, the interleaving sequence shown in Equation 11 is optimized when 16-symbol mapping (in particular, NUC symbol mapping) is used and an LDPC encoder having a length of 16200 and a code rate of 2/15 is used.

7 is a block diagram illustrating a bit interleaver according to an embodiment of the present invention.

Referring to FIG. 7 , the bit interleaver according to an embodiment of the present invention includes memories 710 and 730 and a processor 720 .

The memory 710 stores an LDPC codeword having a length of 16200 and a code rate of 2/15.

The processor 720 generates an interleaved codeword by interleaving the LDPC codeword in units of bit groups corresponding to a parallel factor of the LDPC codeword.

In this case, the parallel factor may be 360. In this case, the bit group may include 360 bits.

In this case, the LDPC codeword can be divided into 45 bit groups as shown in Equation 9 above.

In this case, interleaving may be performed using Equation (10) using a permutation order.

In this case, the permutation order may correspond to the interleaving sequence expressed by Equation (11).

The memory 730 provides the interleaved codeword as a modulator for 16-symbol mapping.

In this case, the modulator may be a symbol mapping device that performs NUC (Non-Uniform Constellation) symbol mapping.

The memory 710 and the memory 730 may correspond to various hardware for storing a set of bits, and data structures such as an array, a list, a stack, and a queue ( data structure).

In this case, the memory 710 and the memory 730 are not physically separate devices, but may physically correspond to different addresses of one device. That is, the memory 710 and the memory 730 are not physically separated, but may be separated only logically.

The error correction encoder 13 shown in FIG. 1 may be implemented in the same structure as in FIG. 7 .

That is, the error correction encoder may include memories and a processor. In this case, the first memory may be a memory for storing an LDPC codeword having a length of 16200 and a code rate of 2/15, and the second memory may be a memory initialized to 0.

The memories may correspond to λ _i (i=0, 1, ..., N-1) and P _j (j=0, 1, ..., M ₁ +M ₂ -1), respectively.

The processor may generate the LDPC codeword corresponding to information bits by performing accumulation on the memory using a sequence corresponding to a parity check matrix.

In this case, the accumulation may be performed on parity bit addresses updated using a sequence of the table.

At this time, the LDPC codeword corresponds to the information bits and has a length of 2160 (=K), a systematic part (λ ₀ , λ ₁ , ..., λ _K-1 ) included in the parity check matrix. The first parity part (λ _K , λ _K+1 , ..., λ _K+M1-1 ) corresponding to the double diagonal matrix and having a length of 3240 (=M ₁ =g) and the identity included in the parity check matrix It may include a second parity part (λ _K+M1 , λ _K+M1+1 , ..., λ _K+M1+M2-1 ) corresponding to the matrix and having a length of 10800 (=M ₂ ).

At this time, the sequence is a value obtained by dividing 2160, which is the length of the systematic part, by 360, which is the CPM size (L) corresponding to the parity check matrix, and 3240, which is the length (M ₁ ) of the first parity part, divided by 360. It may have as many rows as the sum (2160/360+3240/360=15).

As described above, a sequence may be represented by the table.

In this case, the second memory may have a size corresponding to the sum (M ₁ +M ₂ ) of the length (M ₁ ) of the first parity part and the length (M ₂ ) of the second parity part.

In this case, the parity bit addresses may be updated based on a result of comparing each of the previous parity bit addresses (x) and the length (M ₁ ) of the first parity part indicated in each row of the sequence.

That is, the parity bit addresses may be updated according to Equation 5 above. In this case, x is the previous parity bit address, m is an information bit index, an integer greater than 0 and less than L, L is the CPM size of the parity check matrix, Q ₁ is M ₁ /L, M ₁ is the first parity part The size of Q ₂ may be M ₂ /L, and M ₂ may be the size of the second parity part.

In this case, as described above, the accumulation may be performed by changing the rows of the sequence in units of the CPM size L=360 of the parity check matrix.

In this case, the first parity parts λ _K , λ _K+1 , ..., λ _K+M1-1 are parity interleaving using the first memory and the second memory, as described in Equation 7 above. (parity interleaving) may be performed.

At this time, the second parity part (λ _K+M1 , λ _K+M1+1 , ..., λ _K+M1+M2-1 ) is the first parity part (λ _K ) as described through Equation (8). , λ _K+1 , ..., λ _K+M1-1 ) After generation of the first parity part (λ _K , λ _K+1 , ..., λ _K+M1-1 ) and the sequence After the accumulation performed by using the ?, it may be generated by performing parity interleaving using the first memory and the second memory.

8 is an operation flowchart illustrating a bit interleaving method according to an embodiment of the present invention.

Referring to FIG. 8, in the bit interleaving method according to an embodiment of the present invention, an LDPC codeword having a length of 16200 and a code rate of 2/15 is stored (S810).

(N _ldpc 는 16200)와 같이 표현되고, 상기 수학식 9와 같이 각각 360개의 비트들로 구성된 45개의 비트그룹들로 분할될 수 있다.In this case, the LDPC codeword is

( N _ldpc is 16200), and can be divided into 45 bit groups each consisting of 360 bits as in Equation 9 above.

Also, in the bit interleaving method according to an embodiment of the present invention, the interleaved codeword is generated by interleaving the LDPC codeword in units of bit groups having a size corresponding to a parallel factor of the LDPC codeword (S820). ).

In this case, interleaving may be performed using Equation (10) using a permutation order.

In this case, the permutation order may correspond to the interleaving sequence expressed by Equation (11).

In this case, the parallel factor may be 360, and the bit group may include 360 bits.

Also, in the bit interleaving method according to an embodiment of the present invention, the interleaved codeword is output to a modulator for 16-symbol mapping (S830).

As described above, in the bit interleaver, BICM apparatus, and bit interleaving method according to the present invention, the configuration and method of the embodiments described above are not limitedly applicable, but the embodiments are each so that various modifications can be made. All or some of the embodiments may be selectively combined and configured.

710, 730: memory
720: processor

Claims (18)

delete storing an LDPC codeword having a length of 16200 and a code rate of 2/15;
generating an interleaved codeword by interleaving the LDPC codeword in units of bit groups; and
outputting the interleaved codeword for 16-symbol mapping,
The interleaving is
It is performed using the following equation using a permutation order,
[Equation]

( X _j is the j-th bit group, Y _j is the interleaved j-th bit group, π( j ) is the permutation order for interleaving per bit group, N _group is the number of bit groups)
The permutation order is
A bit interleaving method, characterized in that it corresponds to the following interleaving sequence.
[Interleaving Sequence]
={5 33 18 8 29 10 21 14 30 26 11 23 27 4 7 6 24 44 38 31 34 43 13 0 15 42 17 2 20 12 40 39 35 32 1 3 41 37 9 25 19 22 16 28 36} 3. The method according to claim 2,
The LDPC codeword is generated using a sequence corresponding to a parity check matrix, and the sequence is represented by the following table.
[table]
Line 1: 2889 3122 3208 4324 5968 7241 13215
Line 2: 281 923 1077 5252 6099 10309 11114
Line 3: 727 2413 2676 6151 6796 8945 12528
Line 4: 2252 2322 3093 3329 8443 12170 13748
Line 5: 575 2489 2944 6577 8772 11253 11657
Line 6: 310 1461 2482 4643 4780 6936 11970
Line 7: 8691 9746 10794 13582
Line 8: 3717 6535 12470 12752
Line 9: 6011 6547 7020 11746
Line 10: 5309 6481 10244 13824
Line 11: 5327 8773 8824 13343
Line 12: 3506 3575 9915 13609
Line 13: 3393 7089 11048 12816
Line 14: 3651 4902 6118 12048
Line 15: 4210 10132 13375 13377 3. The method according to claim 2,
The 16-symbol mapping is a bit interleaving method, characterized in that the NUC (Non-Uniform Constellation) symbol mapping having 16 constellations. 5. The method according to claim 4,
The bit group comprises 360 bits. 6. The method of claim 5,
The LDPC codeword is

( N _ldpc is 16200), and is divided into 45 bit groups each consisting of 360 bits as shown in the following equation.
[Equation]

( X _j is the jth bit group, N _ldpc is 16200, N _group is 45) delete an error correction encoder that outputs an LDPC codeword having a length of 16200 and a code rate of 2/15;
a bit interleaver for outputting the interleaved codeword by interleaving the LDPC codeword in units of bit groups; and
a modulator that performs 16-symbol mapping corresponding to the interleaved codeword;
The interleaving is
It is performed using the following equation using a permutation order,
[Equation]

( X _j is the j-th bit group, Y _j is the interleaved j-th bit group, π( j ) is the permutation order for interleaving per bit group, N _group is the number of bit groups)
The permutation order is
BICM (Bit-Interleaved Coded Modulation) device, characterized in that it corresponds to the following interleaving sequence.
[Interleaving Sequence]
={5 33 18 8 29 10 21 14 30 26 11 23 27 4 7 6 24 44 38 31 34 43 13 0 15 42 17 2 20 12 40 39 35 32 1 3 41 37 9 25 19 22 16 28 36} 9. The method of claim 8,
The LDPC codeword is generated using a sequence corresponding to a parity check matrix, and the sequence is represented by the following table.
[table]
Line 1: 2889 3122 3208 4324 5968 7241 13215
Line 2: 281 923 1077 5252 6099 10309 11114
Line 3: 727 2413 2676 6151 6796 8945 12528
Line 4: 2252 2322 3093 3329 8443 12170 13748
Line 5: 575 2489 2944 6577 8772 11253 11657
Line 6: 310 1461 2482 4643 4780 6936 11970
Line 7: 8691 9746 10794 13582
Line 8: 3717 6535 12470 12752
Line 9: 6011 6547 7020 11746
Line 10: 5309 6481 10244 13824
Line 11: 5327 8773 8824 13343
Line 12: 3506 3575 9915 13609
Line 13: 3393 7089 11048 12816
Line 14: 3651 4902 6118 12048
Line 15: 4210 10132 13375 13377 9. The method of claim 8,
The 16-symbol mapping is a BICM device, characterized in that the NUC (Non-Uniform Constellation) symbol mapping having 16 constellations. 11. The method of claim 10,
The BICM device, characterized in that the bit group includes 360 bits. 12. The method of claim 11,
The LDPC codeword is

( N _ldpc is 16200), and is divided into 45 bit groups each consisting of 360 bits as shown in the following equation.
[Equation]

( X _j is the jth bit group, N _ldpc is 16200, N _group is 45) delete generating an LDPC codeword having a length of 16200 and a code rate of 2/15;
generating an interleaved codeword by interleaving the LDPC codeword in units of bit groups; and
performing 16-symbol mapping corresponding to the interleaved codeword;
The interleaving is
It is performed using the following equation using a permutation order,
[Equation]

( X _j is the j-th bit group, Y _j is the interleaved j-th bit group, π( j ) is the permutation order for interleaving per bit group, N _group is the number of bit groups)
The permutation order is
A broadcast signal transmission method, characterized in that it corresponds to the following interleaving sequence.
[Interleaving Sequence]
={5 33 18 8 29 10 21 14 30 26 11 23 27 4 7 6 24 44 38 31 34 43 13 0 15 42 17 2 20 12 40 39 35 32 1 3 41 37 9 25 19 22 16 28 36} 15. The method of claim 14,
The LDPC codeword is generated using a sequence corresponding to a parity check matrix, and the sequence is represented by the following table.
[table]
Line 1: 2889 3122 3208 4324 5968 7241 13215
Line 2: 281 923 1077 5252 6099 10309 11114
Line 3: 727 2413 2676 6151 6796 8945 12528
Line 4: 2252 2322 3093 3329 8443 12170 13748
Line 5: 575 2489 2944 6577 8772 11253 11657
Line 6: 310 1461 2482 4643 4780 6936 11970
Line 7: 8691 9746 10794 13582
Line 8: 3717 6535 12470 12752
Line 9: 6011 6547 7020 11746
Line 10: 5309 6481 10244 13824
Line 11: 5327 8773 8824 13343
Line 12: 3506 3575 9915 13609
Line 13: 3393 7089 11048 12816
Line 14: 3651 4902 6118 12048
Line 15: 4210 10132 13375 13377 15. The method of claim 14,
The 16-symbol mapping is a non-uniform constellation (NUC) symbol mapping having 16 constellations. 17. The method of claim 16,
The method of transmitting a broadcast signal, characterized in that the bit group includes 360 bits. 18. The method of claim 17,
The LDPC codeword is

( N _ldpc is 16200), and is divided into 45 bit groups each consisting of 360 bits as shown in the following equation.
[Equation]

( X _j is the jth bit group, N _ldpc is 16200, N _group is 45)

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