KR20150112766A - Bit interleaver for 4096-symbol mapping and low density parity check codeword with 64800 length, 5/15 rate, and method using the same - Google Patents

Abstract

Disclosed are a bit interleaver, a BICM device, and a bit interleaving method. The bit interleaver according to an embodiment of the present invention includes: a first memory which stores LDPC code words with the length of 64800 and a code rate of 5/15; a processor which generates an interleaved code word by interleaving the LDPC code word in a bit group unit with the size corresponding to parallel factors for the LDPC code words; and a second memory which provides the interleaved code words to a modulator for 4096-symbol mapping.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bit interleaver for LDPC codeword and 4096-symbol mapping having a length of 64,800 and a code rate of 5/15, and a bit interleaving method using the bit interleaver and a bit interleaving method using the bit interleaver. 15 RATE, AND METHOD USING THE SAME}

The present invention relates to an interleaver, and more particularly, to a bit interleaver for distributing burst errors occurring in a digital broadcast channel.

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

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

Despite these advantages, if the BICM fails to properly distribute burst errors occurring in the channel through a bitwise interleaver, the performance deteriorates drastically. Therefore, the bitwise interleaver used in the BICM should be designed to be optimized to the modulation order, the length of the error correction code, the coding rate, and the like.

It is an object of the present invention to provide a bit interleaver in a BICM capable of effectively dispersing burst errors occurring in a broadcast system channel.

It is also an object of the present invention to provide a bit interleaver which can be applied to a next generation broadcasting system such as ATSC 3.0, optimized for a LDPC encoder with a length of 64,800 and a coding rate of 5/15 and a modulator for performing 4096-symbol mapping .

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 64,800 and a coding rate of 5/15; A processor for interleaving the LDPC codeword in a bit group unit of a size corresponding to a parallel factor of the LDPC codeword to generate an interleaved codeword; And a second memory for providing the interleaved codeword to a modulator for 4096-symbol mapping.

At this time, the 4096-symbol mapping may be a NUC (Non-Uniform Constellation) symbol mapping having 4096 constellations.

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

(N _ldpc 는 64800)와 같이 표현되고, 하기 수학식 9와 같이 각각 360개의 비트들로 구성된 180개의 비트그룹들로 분할될 수 있다.At this time, the LDPC codeword has codewords

( N _ldpc is 64800), and may be divided into 180 bit groups each consisting of 360 bits as shown in Equation (9).

&Quot; (9) "

( X _j is the jth bit group, N _ldpc is 64800, and N _group is 180)

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

&Quot; (10) "

( X _j is a jth bit group, Y _j is an interleaved j th bit group, and? ( J ) is a permutation order for bit group unit interleaving)

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

&Quot; (11) "

Interleaving sequence

= {146 89 57 16 164 138 91 78 90 66 122 12 9 157 14 68 112 128 74 45 28 87 158 56 61 168 18 161 95 99 139 22 65 130 166 118 150 49 142 44 36 1 121 6 46 29 88 47 0 58 105 43 80 64 107 21 55 151 8 145 163 7 98 123 17 11 153 136 52 3 13 34 160 102 125 114 152 84 32 97 33 60 62 79 37 129 38 165 71 75 59 144 127 132 104 53 162 103 120 54 155 116 48 77 76 73 113 119 179 177 41 19 92 109 31 143 178 108 39 140 106 40 5 25 81 176 101 124 126 72 111 4 173 156 134 86 174 2 170 35 175 137 15 24 69 96 30 117 67 171 149 169 63 23 20 167 27 147 51 10 82 131 85 110 94 135 172 148 50 154 42 70 115 26 83 141 100 133 93 159}

Also, the bit interleaving method according to the present invention includes: storing an LDPC codeword having a length of 64,800 and a coding rate of 5/15; Generating interleaved codewords by interleaving the LDPC codewords in a bit group unit of a size corresponding to a parallel factor of the LDPC codeword; And outputting the interleaved codeword to a modulator for 4096-symbol mapping.

Also, the BICM apparatus according to the present invention includes: an error correcting encoder for outputting an LDPC codeword having a length of 64,800 and a coding rate of 5/15; A bit interleaver for interleaving the LDPC codeword in a bit group unit of a size corresponding to a parallel factor of the LDPC codeword and outputting an interleaved codeword; And a modulator for 4096-symbol mapping the interleaved codeword.

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

Also, the present invention provides a bit interleaver that can be applied to a next generation broadcast system such as ATSC 3.0, optimized for a LDPC encoder having a length of 64800 and a sub-efficiency of 5/15 and a modulator for performing 4096-symbol mapping.

1 is a block diagram illustrating a system for transmitting / receiving a broadcast signal according to an embodiment of the present invention.
2 is a flowchart illustrating a method of transmitting / receiving a broadcast signal according to an exemplary 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 64,800.
FIG. 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 a flowchart illustrating a bit interleaving method according to an embodiment of the present invention.

The present invention will now be described in detail with reference to the accompanying drawings. Hereinafter, a repeated description, a known function that may obscure the gist of the present invention, and a detailed description of the configuration will be omitted. Embodiments of the present invention are provided to more fully describe the present invention to those skilled in the art. Accordingly, the shapes and sizes of the elements in the drawings and the like can be exaggerated for clarity.

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 system for transmitting / receiving a broadcast signal 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 perform communication via the wireless channel 20.

The BICM apparatus 10 generates k bits of information bits 11 by encoding the information bits 11 in the error correction coder 13 to form an n-bit codeword. At this time, 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.

At this time, interleaving can be performed on a bit group basis. In this case, the error correction encoder 13 may be an LDPC encoder having a length of 64,800 and a coding rate of 5/15, a codeword having a length of 64,800 may be divided into a total of 180 bit groups, And 360 bits, which is a parallel factor of the codeword.

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

At this time, the bit interleaver 14 effectively dissociates the cluster error occurring in the channel, thereby preventing performance degradation of the error correction code. At this time, the bit interleaver 14 can be designed individually according to the length of the error correction code, the coding rate, and the modulation order.

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

At this time, the modulator 15 is a concept including a symbol mapping device. At this time, the modulator 15 may be a symbol mapping device that performs 4096-symbol mapping that maps codes to 4096 constellations.

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

In particular, the modulator 15 may be a symbol mapping device that performs NUC (Non-Uniform Constellation) symbol mapping with 4096 constellations.

The signal transmitted through the wireless channel 20 is received via the antenna 31 of the BICM receiving apparatus 30 and the BICM receiving apparatus 30 undergoes the reverse process of the process occurring in the BICM apparatus 10. [ That is, the received data is demodulated by the demodulator 33, deinterleaved by the bit deinterleaver 34, and decoded by the error correction decoder 35 to finally recover the information bits.

It will be apparent to those skilled in the art that the above-described transmission / reception process is described within the minimum range necessary to explain the features of the present invention, and that many other processes necessary for data transmission can be added.

2 is a flowchart illustrating a method of transmitting / receiving a broadcast signal according to an exemplary embodiment of the present invention.

Referring to FIG. 2, a method for transmitting / receiving a broadcast signal according to an embodiment of the present invention first performs error correction coding of input bits (S210).

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

In this case, step S210 may be performed in the same manner as the LDPC coding method described later.

In addition, in the broadcast signal transmitting / receiving method, interleaved codewords are generated by interleaving n-bit codewords in bit group units (S220).

In this case, the n-bit codeword may be an LDPC codeword having a length of 64,800 and a coding rate of 5/15, a codeword having a length of 64,800 may be divided into a total of 180 bit groups, each of the bit groups may be an LDPC codeword May include 360 bits corresponding to a parallel factor of < RTI ID = 0.0 >

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

Also, the broadcasting signal transmitting / receiving method modulates the encoded data (S230).

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

At this time, the modulator is a concept including a symbol mapping device. At this time, the modulator may be a symbol mapping device that performs 4096-symbol mapping that maps codes to 4096 constellations.

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

In particular, the modulator may be a symbol mapping device that performs NUC (Non-Uniform Constellation) symbol mapping with 4096 constellations.

In addition, the broadcasting signal transmitting / receiving method transmits the modulated data (S240).

That is, in step S240, the modulated codeword is transmitted on the wireless channel through the antenna.

In addition, the broadcasting signal transmitting / receiving method demodulates the received data (S250).

That is, the step S250 receives the signal transmitted through the radio channel through the antenna of the receiver and demodulates the received data by the demodulator.

Also, the broadcasting signal transmitting / receiving method deinterleaves the demodulated data (S260). At this time, the deinterleaving in step S260 may correspond to an inverse process of step S220.

Also, the broadcasting signal transmitting / receiving method performs error correction decoding on the deinterleaved codeword (S270).

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

In this case, step S270 may correspond to an inverse process of an LDPC encoding method to be described later.

The LDPC (Low Density Parity Check) code is known as a code close to the Shannon limit in an AWGN (Additive White Gaussian Noise) channel. The LDPC code is asymptotically superior to the turbo code, .

Generally, an LDPC code is defined by a randomly generated low density PCM (Parity Check Matrix). However, a randomly generated LDPC code not only requires a large amount of memory to store the PCM, but also takes a long time to access the memory. In order to solve such a problem, a quasi-cyclic LDPC (QC-LDPC) code has been proposed, and a QC-LDPC code composed of a zero matrix or a CPM (Circulant Permutation Matrix) Lt; RTI ID = 0.0 > PCM. ≪ / RTI >

[Equation 1]

Here, J is a CPM whose size is L x L and is given by the following equation (2). In the following, L may be 360.

&Quot; (2) "

In addition, J ⁱ is the L x L identity matrix I (= J ⁰ ) shifted to the right i (0 = i L) times, and J ^∞ is the L x L zero matrix. Therefore, in the QC-LDPC code, only the exponent ^{i needs} to be stored in order to store J ⁱ , so that 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 the matrices A and C are g x K and (N-K-g) x (K + g), respectively. The matrix Z is a zero matrix whose magnitude is gx (NKg), the matrix D is an identity matrix whose magnitude is (NKg) x (NKg), the 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 elements and the elements neighboring the lower diagonal are 0, and may be defined as Equation (3).

&Quot; (3) "

Where I _LxL is an identity matrix of size L x L.

That is, the matrix B may be a general (bit-wise) diagonal diagonal matrix or a block-wise diagonal matrix as shown in Equation (3). A bit-wise double diagonal matrix is disclosed in detail in Korean Patent Publication No. 2007-0058438.

Particularly, when the matrix B is a bit-wise diagonal matrix, row permutation or column permutation is applied to the PCM of the structure shown in FIG. 3 including the matrix B It will be apparent to those skilled in the art that it may be converted to quasi-cyclic.

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

The present invention proposes a newly designed QC-LDPC code having a code rate of 5/15 and a codeword length of 64,800 as shown in Table 1 below. That is, an LDPC code generating an LDPC codeword having a length of 16,400 is proposed by receiving information having a length of 21600.

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 can be displayed in a sequence, and an equivalent relation between the sequence and the matrix (parity bit check matrix) is established, and the sequence can be expressed as shown in the following table.

[table]

1st line: 221 1011 1218 4299 7143 8728 11072 15533 17356 33909 36833

Second line: 360 1210 1375 2313 3493 16822 21373 23588 23656 26267 34098

Third line: 544 1347 1433 2457 9186 10945 13583 14858 19195 34606 37441

Line 4: 37 596 715 4134 8091 12106 24307 24658 34108 40591 42883

5th line: 235 398 1204 2075 6742 11670 13512 23231 24784 27915 34752

6th line: 204 873 890 13550 16570 19774 34012 35249 37655 39885 42890

7th line: 221 371 514 11984 14972 15690 28827 29069 30531 31018 43121

Line 8: 280 549 1435 1889 3310 10234 11575 15243 20748 30469 36005

9th line: 223 666 1248 13304 14433 14732 18943 21248 23127 38529 39272

10th line: 370 819 1065 9461 10319 25294 31958 33542 37458 39681 40039

11th line: 585 870 1028 5087 5216 12228 16216 16381 16937 27132 27893

Line 12: 164 167 1210 7386 11151 20413 22713 23134 24188 36771 38992

Line 13: 298 511 809 4620 7347 8873 19602 24162 29198 34304 41145

Line 14: 105 830 1212 2415 14759 15440 16361 16748 22123 32684 42575

Line 15: 659 665 668 6458 22130 25972 30697 31074 32048 36078 37129

Line 16: 91 808 953 8015 8988 13492 13987 15979 28355 34509 39698

Line 17: 594 983 1265 3028 4029 9366 11069 11512 27066 40939 41639

Line 18: 506 740 1321 1484 10747 16376 17384 20285 31502 38925 42606

19th line: 338 356 975 2022 3578 18689 18772 19826 22914 24733 27431

20th line: 709 1264 1366 4617 8893 25226 27800 29080 30277 37781 39644

21st line: 840 1179 1338 2973 3541 7043 12712 15005 17149 19910 36795

22nd line: 1009 1267 1380 4919 12679 22889 29638 30987 34637 36232 37284

Line 23: 466 913 1247 1646 3049 5924 9014 20539 34546 35029 36540

24th line: 374 697 984 1654 5870 10883 11684 20294 28888 31612 34031

Line 25: 117 240 635 5093 8673 11323 12456 14145 21397 39619 42559

26th line: 122 1265 1427 13528 14282 15241 16852 17227 34723 36836 39791

27th line: 595 1180 1310 6952 17916 24725 24971 27243 29555 32138 35987

Line 28: 140 470 1017 13222 13253 18462 20806 21117 28673 31598 37235

Line 29: 7 710 1072 8014 10804 13303 14292 16690 26676 36443 41966

30th line: 48 189 759 12438 14523 16388 23178 27315 28656 29111 29694

Line 31: 285 387 410 4294 4467 5949 25386 27898 34880 41169 42614

Line 32: 474 545 1320 10506 13186 18126 27110 31498 35353 36193 37322

Line 33: 1075 1130 1424 11390 13312 14161 16927 25071 25844 34287 38151

34th line: 161 396 427 5944 17281 22201 25218 30143 35566 38261 42513

35th line: 233 247 694 1446 3180 3507 9069 20764 21940 33422 39358

36th line: 271 508 1013 6271 21760 21858 24887 29808 31099 35475 39924

37th line: 8 674 1329 3135 5110 14460 28108 28388 31043 31137 31863

38th line: 1035 1222 1409 8287 16083 24450 24888 29356 30329 37834 39684

39th line: 391 1090 1128 1866 4095 10643 13121 14499 20056 22195 30593

40th line: 55 161 1402 6289 6837 8791 17937 21425 26602 30461 37241

41st line: 110 377 1228 6875 13253 17032 19008 23274 32285 33452 41630

Line 42: 360 638 1355 5933 12593 13533 23377 23881 24586 26040 41663

Line 43: 535 1240 1333 3354 10860 16032 32573 34908 34957 39255 40759

44th line: 526 936 1321 7992 10260 18527 28248 29356 32636 34666 35552

Line 45: 336 785 875 7530 13062 13075 18925 27963 28703 33688 36502

46th line: 36 591 1062 1518 3821 7048 11197 17781 19408 22731 24783

47th line: 214 1145 1223 1546 9475 11170 16061 21273 38688 40051 42479

Line 48: 1136 1226 1423 20227 22573 24951 26462 29586 34915 42441 43048

Line 49: 26 276 1425 6048 7224 7917 8747 27559 28515 35002 37649

Line 50: 127 294 437 4029 8585 9647 11904 24115 28514 36893 39722

51st line: 748 1093 1403 9536 19305 20468 31049 38667 40502 40720 41949

52th line: 96 638 743 9806 12101 17751 22732 24937 32007 32594 38504

53rd line: 649 904 1079 2770 3337 9158 20125 24619 32921 33698 35173

54th line: 401 518 984 7372 12438 12582 18704 35874 39420 39503 39790

55th line: 10 451 1077 8078 16320 17409 25807 28814 30613 41261 42955

56th line: 405 592 1178 15936 18418 19585 21966 24219 30637 34536 37838

Line 57: 50 584 851 9720 11919 22544 22545 25851 35567 41587 41876

58th line: 911 1113 1176 1806 10058 10809 14220 19044 20748 29424 36671

59th line: 441 550 1135 1956 11254 18699 30249 33099 34587 35243 39952

Line 60: 510 1016 1281 8621 13467 13780 15170 16289 20925 26426 34479

Line 61: 4969 5223 17117 21950 22144 24043 27151 39809

Line 62: 11452 13622 18918 19670 23995 32647 37200 37399

Line 63: 6351 6426 13185 13973 16699 22524 31070 31916

Line 64: 4098 10617 14854 18004 28580 36158 37500 38552

The LDPC codes in the form of a sequence are 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, an LDPC code denoted by a sequence is encoded as follows. Assume an information block S = (s ₀ , s ₁ , ..., s _{K - 1} ) with an information size _K. An LDPC encoder uses an information block S having a size K to generate a codeword having a size of N = K + M ₁ + M ₂ ,

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

- initialization:

&Quot; (4) "

를 상기 테이블의 수열의 제1행에 명시된 패러티 비트 주소들(parity bit addresses)에서 누적(accumulate)한다. 예를 들어, 길이가 64800이며, 부호율이 5/15인 LDPC 부호에서의 누적 과정은 다음과 같다.-first

At the parity bit addresses specified in the first row of the table's sequence. For example, the accumulation process for an LDPC code with a length of 64800 and a code rate of 5/15 is as follows.

)은 GF(2)에서 일어난다.Here, add (

) Occurs in GF (2).

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

Are accumulated at the parity bit addresses calculated in Equation (5) below.

&Quot; (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 64800이며, 부호율이 5/15인 LDPC 부호는 M₁ = 1440, Q₁ = 4, M₂ = 41760, Q₂ = 116, L = 360이므로, 두 번째 비트

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

Q ₁ = M ₁ / L, Q ₂ = M ₂ / L, and L = 360, which are the parity bit addresses corresponding to the parity bit addresses corresponding to the parity bits in the table. Q ₁ and Q ₂ are defined in Table 2 below. For example, the LDPC code having a length of 64,800 and a code rate of 5/15 is M ₁ = 1440, Q ₁ = 4, M ₂ = 41760, Q ₂ = 116,

Using Equation (5), the following operation is performed.

Table 2 shows the sizes of M ₁ , M ₂ , Q ₁ and 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

The new 360 information bits up to < RTI ID = 0.0 > Eq. 5 < / RTI > calculate and accumulate the addresses of the parity bit accumulators from Equation 5 using the second row of the sequence.

Similarly, for all groups of new L information bits, the address of the parity bit accumulators from Equation (5) is calculated and accumulated using a new row of the sequences.

에서

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

in

All the information bits up to i = 1 are used, and then the operation of Equation (6) is sequentially performed starting from i = 1.

&Quot; (6) "

Next, when parity interleaving is performed as shown in Equation (7), parity generation corresponding to the diagonal diagonal matrix B is completed.

&Quot; (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 diagonal diagonal matrix B is completed, M ₁ generated parity (

), And generates 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.-

in

For each group consisting of L bits from the first diagonal matrix B to the new row of the series (starting from the immediately following row of the last row used to generate the parity corresponding to the diagonal diagonal matrix B) To calculate the addresses of the parity bit accumulators, and to perform related calculations.

에서

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

in

And parity interleaving as shown in Equation (8) below is performed, parity generation corresponding to the identity matrix D is completed.

&Quot; (8) "

4 is a diagram illustrating bit groups of an LDPC codeword having a length of 64,800.

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 to 179 ^th groups).

In this case, 360 may be a parallel factor (PF) of an LDPC codeword. That is, since the PF is 360, the 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.

FIG. 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 an 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 by the designed interleaving sequence.

For example, suppose that the interleaving sequence for an LDPC codeword of length 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 the 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 24th bit group of the LDPC codeword 610 is interleaved with the LDPC codeword 620 by the interleaving sequence. The 34th bit group of the LDPC codeword 610 becomes the first bit group of the interleaved LDPC codeword 620 and the 15th bit group of the LDPC codeword 610 is interleaved The 11th bit group of the LDPC codeword 610 becomes the third bit group of the interleaved LDPC codeword 620 and the second bit group of the LDPC codeword 620 becomes the second bit group of the LDPC codeword 620, Th bit group becomes the fourth bit group of the interleaved LDPC codeword 620. [

는 N _group = N _ldpc / 360 개의 비트그룹들로 쪼개어진다.LDPC codeword with length N _ldpc

Is divided into N _group = N _ldpc / 360 bit groups.

&Quot; (9) "

Here, X _j denotes a 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).

&Quot; (10) "

Here, Y _j denotes an interleaved jth bit group, and [pi] ( j ) is a permutation order for bit group unit interleaving. The permutation order corresponds to the interleaving sequence of Equation (11).

&Quot; (11) "

Interleaving sequence

= {146 89 57 16 164 138 91 78 90 66 122 12 9 157 14 68 112 128 74 45 28 87 158 56 61 168 18 161 95 99 139 22 65 130 166 118 150 49 142 44 36 1 121 6 46 29 88 47 0 58 105 43 80 64 107 21 55 151 8 145 163 7 98 123 17 11 153 136 52 3 13 34 160 102 125 114 152 84 32 97 33 60 62 79 37 129 38 165 71 75 59 144 127 132 104 53 162 103 120 54 155 116 48 77 76 73 113 119 179 177 41 19 92 109 31 143 178 108 39 140 106 40 5 25 81 176 101 124 126 72 111 4 173 156 134 86 174 2 170 35 175 137 15 24 69 96 30 117 67 171 149 169 63 23 20 167 27 147 51 10 82 131 85 110 94 135 172 148 50 154 42 70 115 26 83 141 100 133 93 159}

That is, when each of the codeword and the interleaved codeword includes 180 bit groups from the 0 < th > bit group to the 179 < th > bit group, the interleaving sequence of Equation (11) The 89th bit group of the codeword becomes the first bit group of the interleaved codeword and the 57th bit group of the codeword becomes the second bit group of the interleaved codeword, The 16th bit group of the codeword becomes the 3rd bit group of the interleaved codeword, ..., the 93rd bit group of the codeword becomes the 178th bit group of the interleaved codeword, and the 159th bit group of the codeword becomes the The 179th bit group of the interleaved codeword.

In particular, the interleaving sequence shown in Equation (11) is optimized when a 4096-symbol mapping (especially NUC symbol mapping) is used and an LDPC encoder with a length of 64800 and a coding rate of 5/15 is used.

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

Referring to FIG. 7, a 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 64,800 and a coding rate of 5/15.

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

At this time, the parallel factor may be 360. At this time, the bit group may include 360 bits.

At this time, the LDPC codeword can be divided into 180 bit groups as shown in Equation (9).

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

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

The memory 730 provides the interleaved codeword to a modulator for 4096-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 may include data structures such as an array, a list, a stack, a queue, data structure.

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

The error correcting encoder 13 shown in FIG. 1 may be implemented by the structure shown in FIG.

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 64,800 and a coding rate of 5/15, and the second memory may be a memory initialized to zero.

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

The processor may accumulate the memory using a sequence corresponding to a parity check matrix to generate the LDPC codeword corresponding to the information bits.

At this time, the accumulation may be performed at parity bit addresses that are updated using the sequence of the table.

In this case, the LDPC codeword includes a systematic part (λ ₀ , λ ₁ ,..., Λ _{K -1} ) corresponding to the information bits and having a length of 21600 (= K) dual corresponding to a diagonal matrix, and a length of 1440 (= M ₁ = g) of the first parity part _{(λ K, λ K + 1} , ..., λ K + M1-1) , and the identity included in the parity check matrix It corresponds to the matrix and may include a length of 41760 (= ₂ M) of the second parity part _{(λ K + M1, λ K} + M1 + 1, ..., λ K + M1 + M2- 1).

In this case, a value obtained by dividing 21600, which is the length of the systematic part, by the CPM size (L) 360 corresponding to the parity check matrix, and 1440, which is the length (M ₁ ) of the first parity part, (21600/360 + 1440/360 = 64) rows.

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

At this time, 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.

At this time, the parity bit addresses may be updated based on the result of comparing each of the previous parity bit addresses (x) shown in each row of the series with the length (M ₁ ) of the first parity part.

That is, the parity bit addresses can be updated by Equation (5). Where m is an integer greater than 0 and less than L, and L is the CPM size of the parity check matrix, Q ₁ is M ₁ / L, and M ₁ is the first parity part Q ₂ may be M ₂ / L, and M ₂ may be the size of the second parity part.

At this time, the accumulation may be performed while changing the rows of the sequence with the CPM size L = 360 units of the parity check matrix as described above.

In this case, the first parity part (? _{K ,? K + 1} , ...,? _{K + M1-1} ) has parity interleaving using the first memory and the second memory, (parity interleaving).

At this time, the second parity part _{(M1 + K} λ, λ _{K + M1 + 1,} ..., λ _{K + M1 + M2- 1)} includes a first parity part (λ _K, as described through the equation (8), after the generation of _{λ K + 1, ..., λ} K + M1-1) has completed the first parity part _{(λ K, λ K + 1} , ..., λ K + M1-1) and the sequence And performing parity interleaving using the first memory and the second memory after the accumulation performed using the first memory and the second memory is completed.

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

Referring to FIG. 8, a bit interleaving method according to an embodiment of the present invention stores an LDPC codeword having a length of 64,800 and a coding rate of 5/15 (S810).

(N _ldpc 는 64800)와 같이 표현되고, 상기 수학식 9와 같이 각각 360개의 비트들로 구성된 180개의 비트그룹들로 분할될 수 있다.At this time, the LDPC codeword

( N _ldpc is 64800), and can be divided into 180 bit groups each consisting of 360 bits as shown in Equation (9).

In addition, the bit interleaving method according to an embodiment of the present invention interleaves the LDPC codeword in units of a bit group of a size corresponding to a parallel factor of the LDPC codeword to generate an interleaved codeword (S820 ).

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

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

At this time, the parallel factor is 360, and the bit group may include 360 bits.

In addition, the bit interleaving method according to an embodiment of the present invention outputs the interleaved codeword to a modulator for 4096-symbol mapping (S830).

As described above, the bit interleaver, the BICM device, and the bit interleaving method according to the present invention are not limited to the configuration and method of the embodiments described above. All or some of the embodiments may be selectively combined.

710, 730: memory
720: Processor

Claims (6)

A first memory for storing an LDPC codeword having a length of 64,800 and a code rate of 5/15;
A processor for interleaving the LDPC codeword in a bit group unit of a size corresponding to a parallel factor of the LDPC codeword to generate an interleaved codeword; And
A second memory that provides the interleaved codeword to a modulator for 4096-symbol mapping;
Bit interleaver. The method according to claim 1,
Wherein the 4096-symbol mapping is a Non-Uniform Constellation (NUC) symbol mapping having 4096 constellations. The method of claim 2,
Wherein the parallel factor is 360 and the bit group comprises 360 bits. The method of claim 3,
The LDPC codeword

( N _ldpc is 64800), and is divided into 180 bit groups each consisting of 360 bits as shown in the following equation.
[Mathematical Expression]

( X _j is the jth bit group, N _ldpc is 64800, and N _group is 180) The method of claim 4,
The interleaving
Wherein the bit interleaver is performed using the following equation using a permutation order.
[Mathematical Expression]

( X _j is a jth bit group, Y _j is an interleaved j th bit group, and? ( J ) is a permutation order for bit group unit interleaving) The method of claim 5,
The permutation order
Wherein the interleaving sequence corresponds to an interleaving sequence represented by the following equation:
[Mathematical Expression]
Interleaving sequence
= {146 89 57 16 164 138 91 78 90 66 122 12 9 157 14 68 112 128 74 45 28 87 158 56 61 168 18 161 95 99 139 22 65 130 166 118 150 49 142 44 36 1 121 6 46 29 88 47 0 58 105 43 80 64 107 21 55 151 8 145 163 7 98 123 17 11 153 136 52 3 13 34 160 102 125 114 152 84 32 97 33 60 62 79 37 129 38 165 71 75 59 144 127 132 104 53 162 103 120 54 155 116 48 77 76 73 113 119 179 177 41 19 92 109 31 143 178 108 39 140 106 40 5 25 81 176 101 124 126 72 111 4 173 156 134 86 174 2 170 35 175 137 15 24 69 96 30 117 67 171 149 169 63 23 20 167 27 147 51 10 82 131 85 110 94 135 172 148 50 154 42 70 115 26 83 141 100 133 93 159}

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