KR20150029534A

KR20150029534A - Ldpc(low density parity check) - rs(reed solomon) 2-dimensional code for terrestrial cloud broadcasting

Info

Publication number: KR20150029534A
Application number: KR20140102102A
Authority: KR
Inventors: 박성익; 권선형; 김흥묵; 허남호
Original assignee: 한국전자통신연구원
Priority date: 2013-09-10
Filing date: 2014-08-08
Publication date: 2015-03-18
Also published as: KR102043663B1

Abstract

And a low density parity check (LDPC) -Red Solomon (LD) two-dimensional code for terrestrial cloud broadcasting. A method of transmitting a terrestrial cloud broadcast signal may include encoding information to be transmitted into a two-dimensional code composed of an LDPC code and an RS code, and outputting the information encoded in the two-dimensional code on a row-by-row basis.

Description

(LDPC (LOW DENSITY PARITY CHECK) - RS (REED SOLOMON) 2-DIMENSIONAL CODE FOR TERRESTRIAL CLOUD BROADCASTING for terrestrial cloud broadcast}

Embodiments of the present invention are directed to a terrestrial cloud broadcasting system operating in a single frequency network, in which a low density parity check (LDPC) code and a reed solomon (RS) code are used to correct an error occurring in a wireless channel And to a constructed two-dimensional code.

Current terrestrial TV broadcasts generate co-channel interference that is three times the service radius, so the same frequency can not be reused within three times the service radius. The area where the same frequency can not be reused is called a white space, and the spectrum efficiency is very low due to occurrence of a white space. Therefore, as a method for improving the spectral efficiency, there has been a need to develop a transmission technique that not only increases the transmission capacity but also eliminates white space and emphasizes reception robustness and facilitates frequency reuse.

Accordingly, IEEE Transactions on Broadcasting, vol. 58, no. 3, the terrestrial cloud broadcasting technology, which is easy to reuse frequency and does not generate whitespace, and is easy to construct and operate a single frequency network, is disclosed in the publication "Cloud Transmission: A New Spectrum-Reuse Friendly Digital Terrestrial Broadcasting Transmission System" It was proposed.

With such a terrestrial cloud broadcasting technology, broadcasters can transmit different broadcasting contents through the same broadcasting channel nationwide or by each region. However, in order to achieve this, the receiver must be able to receive one or more terrestrial cloud broadcast signals in a region where signals transmitted from different transmitters overlap in a single frequency network, that is, in an overlapped region, and demodulate the received terrestrial cloud broadcast signals Should be able to. That is, in a situation where co-channel interference exists and the timing and frequency synchronization of each transmission signal is not guaranteed, the receiver must be able to demodulate one or more cloud broadcast signals. To this end, the terrestrial cloud broadcasting system must operate in a negative SNR (Signal to Noise Ratio) environment where the power of the noise is greater than the power of the broadcast signal.

In addition, terrestrial cloud broadcasting systems are generally designed to take worst cases to provide quality services to all viewers. That is, the viewer is designed to receive the terrestrial broadcasting signal stably at the edge of the broadcasting area (the end or boundary). This means that in most broadcast areas it has a much higher SNR than the edge. For example, it is known that more than 80% of broadcast stations have SNRs greater than 5 decibels (dB) above the edges. Therefore, the terrestrial cloud broadcasting system should be able to decode information with low latency and complexity in regions with low SNR in regions with high SNR.

An object of the present invention is to provide a method and apparatus for operating in a negative SNR (Signal to Noise Ratio) environment for terrestrial cloud broadcasting and an LDPC (Low Latency) Low Density Parity Check) -RS (Reed Solomon) two-dimensional code.

According to an aspect of the present invention, there is provided a method of transmitting a terrestrial cloud broadcast signal, the method comprising: encoding information to be transmitted into a two-dimensional code composed of a Low Density Parity Check (LDPC) code and a Reed Solomon (RS) code; And outputting information on a row-by-row basis.

In one embodiment, the two-dimensional code may be a code in which a row corresponds to the RS code and a column corresponds to the LDPC code.

In another embodiment, the LDPC code may be a QC (Quasi-Cyclic) LDPC code.

In yet another embodiment, the LDPC code may be an A matrix having a size of g × K, a B matrix having a size of g × g, a C matrix having a size of (NKg) × (K + g) NKg) and a Z matrix having a size of gx (NKg), where N is a length of a codeword, K is a length of information, and g is a value varying according to a coding rate.

In another embodiment, the encoding step may be a step of encoding the information to be transmitted primarily on a line-by-line basis using the RS code, and encoding the information to be transmitted on a column basis using the LDPC code.

In yet another embodiment, the encoding step may further include dividing the information encoded by the two-dimensional code into a plurality of blocks based on the size of the circular permutation matrix constituting the LDPC code.

In yet another embodiment, the step of outputting may include outputting the information divided into the plurality of blocks in block units.

In yet another embodiment, the step of outputting may output the information divided into the plurality of blocks in a bit unit.

In another embodiment, the information encoded by the two-dimensional code may be recovered by partial decoding using information constituting the LDPC codeword and a partial parity when the signal-to-noise ratio for the received signal is equal to or larger than the first threshold value.

In another embodiment, the information encoded by the two-dimensional code can be recovered only by RS decoding without LDPC decoding when the SNR of the received signal is equal to or larger than the second threshold.

According to another aspect of the present invention, a transmitting apparatus for transmitting a terrestrial cloud broadcast signal includes: a coding unit for coding information to be transmitted into a two-dimensional code composed of LDPC (Low Density Parity Check) codes and RS (Reed Solomon) codes; And an output unit for outputting the encoded information on a row-by-row basis.

Information can be decoded even in a negative SNR (Signal to Noise Ratio) environment by using a two-dimensional code composed of an LDPC (Low Density Parity Check) code and an RS (Reed Solomon) code. In an environment with a high SNR, It is possible to decode information successfully.

Because it uses adaptive decoding algorithm with different complexity and latency according to SNR, information can be decoded with minimum complexity and latency in an environment with high SNR.

1 is a diagram illustrating a parity check matrix of a QC-LDPC code applied to the present invention.
2 is a diagram illustrating a structure of an LDPC-RS two-dimensional code according to the present invention.
3 is a diagram illustrating a process of encoding information using an LDPC-RS two-dimensional code according to the present invention.
4 is a graph showing BER performance in an AWGN channel of an LDPC-RS two-dimensional code according to the present invention.
5 is a graph showing BER performance in a fading channel of an LDPC-RS two-dimensional code according to the present invention.
6 is a diagram showing an LDPC-RS two-dimensional code in which information for RS encoding is arranged horizontally.
7 is a diagram showing an LDPC-RS two-dimensional code in a form in which information for RS encoding is arranged vertically.
FIG. 8 is a diagram showing that the LDPC-RS two-dimensional codes in FIGS. 6 and 7 are the same in the two-dimensional code view.
9 is a diagram for explaining partial decoding of an LDPC-RS two-dimensional code according to the present invention.
10 and 11 illustrate a method of transmitting information using an LDPC-RS two-dimensional code according to an embodiment of the present invention.
12 is a flowchart illustrating a method of transmitting a terrestrial cloud broadcast signal according to an embodiment of the present invention.
13 is a diagram illustrating a case where only RS decoding is performed on an LDPC-RS two-dimensional code applied to the present invention.
14 is a block diagram showing a transmitting apparatus for transmitting a codeword encoded with an LDPC-RS two-dimensional code according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when an element is referred to as "comprising ", it means that it can include other elements as well, without excluding other elements unless specifically stated otherwise. Also, the terms "to" and the like described in the specification mean a unit for processing at least one function or operation, which can be implemented by hardware, software, or a combination of hardware and software.

1 is a diagram illustrating a parity check matrix of a QC-LDPC code applied to the present invention.

The LDPC (Low Density Parity Check) code is known as an error correcting code that is closest to the Shannon limit in an AWGN (Additive White Gaussian Noise) channel, and has asymptotically superior performance And it is possible to perform parallel decoding. Generally, an LDPC code is defined by a randomly generated low density parity check matrix (PCM). 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.

Therefore, a QC-LDPC code which is an LDPC code having a QC (Quasi-Cyclic) structure can be used to solve such a memory problem. The QC-LDPC code is composed of a zero matrix or a circulant permutation matrix (CPM), and is defined by PCM H as shown in Equation (1).

Here, P is a CPM whose size is L x L , and is expressed by the following equation (2).

Here, P ⁱ is the CPM that size L × L is an identity matrix moved (Identity Matrix) I (= P 0) to the right of i (0≤i <L) times, P ^∞ is of size L × L Spirit It is a zero matrix. Therefore, since the QC-LDPC code only needs to store the exponent ⁱ to store P ⁱ , the memory required to store the PCM is significantly reduced.

Accordingly, QC-LDPC codes defined by the PCM as shown in FIG. 1 can be applied to the present invention. In Fig. 1, N denotes the length of a codeword, and K denotes the length of information. g is a value that varies depending on the coding rate. The matrices A and C are composed of a zero matrix of size L × L and a cyclic permutation matrix of size g × K and (NKg) × (K + g), respectively. The matrix Z is a zero matrix whose magnitude is g × (NKg), and the matrix D is an identity matrix whose magnitude is (NKg) × (NKg). The matrix B is a dual diagonal matrix having a size of g × g, and is expressed by Equation (3).

Where I _L _{× L} represents an identity matrix of size L × L. The diagonal diagonal matrix B has an element matrix constituting the double diagonal line as an identity matrix and a remaining element matrix as a zero matrix as shown in Equation (3). The element matrix constituting the double diagonal line of the double diagonal matrix B can be contiguous with the element matrix constituting the diagonal line of the identity matrix D.

The QC-LDPC code shown in FIG. 1 shows very good performance close to the Shannon limit. In addition, since a part of the parity (the part corresponding to the matrix D ) is constituted by the identity matrix, the code rate is reduced from the mother code having a low code rate through puncturing or truncating technique. Can be easily converted to a higher code. In other words, the QC-LDPC code has a rate-compatible characteristic such as a Raptor code due to a PCM having a special structure as shown in FIG. However, the QC-LDPC code has an error floor phenomenon in a region where the BER (Bit Error Rate) is 10 ^-8 . In addition, since a burst error occurs in the fading channel, a complex bit and frequency interleaver must be used to guarantee performance in the fading channel. Accordingly, in the present invention, information can be encoded using the LDPC-RS two-dimensional code as shown in FIG.

FIG. 2 is a diagram illustrating a structure of an LDPC-RS two-dimensional code according to the present invention, and FIG. 3 is a diagram illustrating a process of coding information using an LDPC-RS two-dimensional code according to the present invention.

2, N _{RS_Info} , N _{RS_Parity,} and N _RS denote information, parity, and codeword lengths for the RS code, and N _{LDPC_Info} , N _{LDPC_Parity,} and N _LDPC represent the lengths of information, parity, The parity, and the length of the codeword. As shown in FIG. 2, a row of an LDPC-RS two-dimensional code according to the present invention corresponds to an RS code, and a column corresponds to an LDPC code. Here, the LDPC code corresponding to the column of the LDPC-RS two-dimensional code may have the same structure as the QC-LDPC code shown in FIG. 1, that is, the same PCM.

Accordingly, the transmitting apparatus for terrestrial cloud broadcasting according to the present invention codes information to be transmitted in a row by row manner using RS codes as shown in FIG. 3, Code can be encoded in a column by column and then output. The receiving apparatus that receives the information (codeword) encoded by the LDPC-RS two-dimensional code can primarily decode the LDPC codeword and decode the RS codeword secondarily.

FIG. 4 is a graph showing BER performance in an AWGN channel of an LDPC-RS two-dimensional code according to the present invention, and FIG. 5 is a graph showing BER performance in a fading channel of an LDPC-RS two-dimensional code according to the present invention.

In FIG. 4, for example, a BER performance of an LDPC code having a length of 16200 or 64800 bits and a code rate of 1/4 and an error of up to 7 bytes is 160 bytes And a BER performance in an AWGN channel of an LDPC-RS two-dimensional code composed of the LDPC code are respectively shown. Quadratic phase shift keying (QPSK) is used as a modulation scheme, and a log-likelihood ratio (LLR) -based sum-product algorithm is used to perform 50 iterative decoding for LDPC codeword decoding. A commonly used hard-decision Berlekamp-Massey algorithm was used to decode RS codewords.

Referring to FIG. 4, the RS output of the LDPC-RS two-dimensional code in the AWGN channel (the output obtained by decoding the RS codeword after decoding the LDPC codeword) shows better performance than the output of the existing LDPC code, The error floor phenomenon is eliminated. Also, it can be seen that the BER performance of the LDPC-RS two-dimensional code shows a sharp-slope gradient than the LDPC code.

Meanwhile, the LDPC-RS two-dimensional codeword according to the present invention can be output in a column by column or in a row by row as shown in Table 1 below.

Output of two-dimensional code effect Case I (column by column)
Output in order of LDPC codeword No interleaving Case II (row by row)
Output in RS codeword order Time & frequency interleaving

Referring to Table 1, Case I, that is, the output in units of columns (output in the order of the LDPC codeword) does not have any interleaving effect, And time and frequency interleaving effects by a block interleaver. Thus, there is no performance difference between Case I and Case II in the AWGN channel, but a very large performance difference is shown in the fading channel as shown in FIG.

In FIG. 5, the LDPC output shows the performance when decoding only the LDPC coders, and the RS output shows the performance when decoding both the LDPC codeword and the RS codeword. The LDPC and RS codes used in FIG. 5 are the same as those in FIG. 4, the length of the LDPC code is 64800 bits, and the error correction capability of the RS code is fixed to 7 bytes. Also, for fading, a TU (Typical Urban) -6 channel at 120 km / h was considered.

As shown in FIG. 5, in the fading channel, the case II has a much better performance than the case I. The reason for this is that Case I (column by column output) can not adequately distribute a large amount of cluster error in the fading channel, while Case II (row by row output) has a time and frequency interleaving effect Block interleaver. Accordingly, the LDPC-RS two-dimensional codeword according to the present invention can be output in units of rows in order to effectively disperse cluster errors generated in the fading panel.

FIG. 6 is a diagram showing an LDPC-RS two-dimensional code in which information for RS coding is arranged horizontally, FIG. 7 is a diagram showing an LDPC-RS two-dimensional code in a form in which information for RS coding is vertically arranged, FIG. 8 is a diagram showing that the LDPC-RS two-dimensional codes in FIGS. 6 and 7 are the same in the two-dimensional code view. Hereinafter, the case where the code rate of the LDPC code is 1/4, the length is 64800 bits, and the length of the RS code is 160 bytes (1280 bits) will be described as an example.

The RS code encodes information in bytes. Therefore, as shown in FIGS. 6 and 7, the LDPC-RS two-dimensional code has a form of arranging input bytes (8 bits) for RS encoding in a row and an input byte for RS encoding in a column Placement is possible. Referring to FIG. 8, the LDPC-RS two-dimensional code applied to the present invention is composed of 8100 RS codewords and 160 LDPC codewords in both cases, which are exactly the same in terms of the two-dimensional code.

9 is a diagram for explaining partial decoding of an LDPC-RS two-dimensional code according to the present invention.

Since the LDPC code used in the LDPC-RS two-dimensional code has a rate-compatible characteristic similar to that of a Raptor code, the code rate can be reduced by puncturing or truncating Can be varied. In other words, the LDPC code can be decoded successfully with only a part of parity and information constituting the LDPC codeword. Therefore, in an area where the signal to noise ratio (SNR) is relatively good, a part of the LDPC codeword (the information part and the parity) is used instead of the decoding using the whole LDPC codeword, that is, A partial decoding can be performed using only a part of the data (e.g., a part), so that the complexity and the latency can be greatly reduced. Here, the complexity means the amount of computation required for decoding, and the latency means the time for the decoder to wait to start decoding. Hereinafter, partial decoding of the LDPC-RS two-dimensional code according to the present invention will be described in more detail with reference to FIG.

The LDPC codeword constituting the LDPC-RS two-dimensional codeword can be divided into a plurality of blocks as shown in FIG. Since the LDPC code used in the LDPC-RS two-dimensional code has the QC structure and the CPM having the size L as described above, the size of the blocks can be determined to be a multiple of L. [ For example, FIG. 9 shows a case where an LDPC codeword having a length of 64800 bits is divided into 2160 blocks having a length of 30 bits (CPM size). The blocks of the divided LDPC codewords can be sequentially transmitted in the horizontal direction as shown in FIG. That is, it can be output in a row by row to obtain time and frequency interleaving effects.

If the vertical LDPC codeword is divided into a plurality of blocks and then transmitted in the horizontal direction, not only the time and frequency interleaving effect due to the block interleaver of the LDPC-RS two-dimensional code but also the rate-compatible LDPC code, Fast decoding with low complexity and latency is possible.

For example, if the receiving apparatus has 780 blocks (540 information blocks + 240 parity blocks), 1080 blocks (540 information blocks + 1620 parity blocks) among the total 2160 blocks (540 information blocks + 1620 parity blocks) (540 information blocks and 540 parity blocks), 1300 blocks (540 information blocks and 760 parity blocks), and 1620 blocks (540 information blocks and 1080 parity blocks), respectively, The code rate and the length of the received LDPC codeword are 23400 bits (16200 bits of information + 7200 bits of parity) of the 2/3 code rate, 32400 bits of the 1/2 code rate (16200 bits of information + 16200 bits of parity ), 39000 bits of the 2/5 code rate (16200 bits of information + 22800 bits of parity), and 1/3 of the code rate of 48600 bits (16200 bits of information + 32400 bits of parity). That is, partial decoding of only a portion of the total 2160 blocks constituting the LDPC codeword results in greater complexity and latency than full decoding of the existing 1/4 code rate and 64800 bit length LDPC code. Can be reduced.

Table 2 below shows the LDPC mother code with a coding rate of 1/4 and the code rate and length of puncturing or truncating LDPC codes, the number of '1's in the PCM, the complexity (Proportional to the number of 1s of PCM) and latency reduction, respectively.

Code rate Length (N) Number of 1 in PCM Complexity Reduction Latency reduction 1/4 64800 277,170 - - 1/3 48600 199,260 28% 25.0% 2/5 39000 160,260 42% 37.5% 1/2 32400 121,190 56% 50.0% 2/3 23400 82,590 70% 62.5%

10 and 11 illustrate a method of transmitting information using an LDPC-RS two-dimensional code according to an embodiment of the present invention.

First, in FIG. 10, 160 1 block among the elementary blocks constituting the LDPC codeword are sequentially transmitted, and then 160 2 blocks are repeatedly transmitted. A method of sequentially transmitting data is shown. On the other hand, in FIG. 11, the first bits of 160 blocks, that is, 160 bits are transmitted, and then the second 160 bits of blocks 1 are transmitted. After repeating this process, A method for transmitting the thirty-first 160 bits of the blocks is shown. The bit-by-bit transmission method as shown in FIG. 11 has an additional bit interleaving effect as compared with the block-by-block transmission method shown in FIG. However, in this case, since the receiver must wait for 4800 bits to receive one block (30 bits), which is a basic block of the LDPC codeword, a longer delay occurs in decoding the LDPC code.

12 is a flowchart illustrating a method of transmitting a terrestrial cloud broadcast signal according to an embodiment of the present invention.

Referring to FIG. 12, the terrestrial cloud broadcast signal transmitting apparatus according to the present invention can encode information (input data) to be transmitted into a two-dimensional code composed of an LDPC code and an RS code (operation 1210). For example, the transmitting apparatus may encode the information to be transmitted primarily on a line-by-line basis using the RS code, and encode the information on a column-by-column basis using the LDPC code. The two-dimensional code may have a row corresponding to the RS code and a column corresponding to the LDPC code. The LDPC code may be an LDPC code of a QC structure.

Then, the encoded information (LDPC-RS codeword) may be outputted in units of rows in order to effectively disperse cluster errors occurring in the fading panel (operation 1220). At this time, the transmission apparatus divides the information encoded by the two-dimensional code into a plurality of blocks based on the size of the cyclic permutation matrix constituting the LDPC code, and outputs information divided into the plurality of blocks on a block- Can be output. It is possible to perform decoding faster than that in the case of outputting in units of bits, and in the case of outputting in units of blocks, there is an effect of additional bit interleaving.

The information encoded with the LDPC-RS two-dimensional code according to the present invention can be successfully restored by the partial decoding using the information constituting the LDPC codeword and a partial parity when the signal-to-noise ratio for the received signal is equal to or larger than the first threshold have. In this case, RS decoding is not performed. The LDPC-RS two-dimensional code-encoded information according to the present invention can be recovered without error by only RS decoding without LDPC decoding when the signal-to-noise ratio for the received signal is equal to or higher than the second threshold.

13 is a diagram illustrating a case where only RS decoding is performed on an LDPC-RS two-dimensional code applied to the present invention.

The LDPC-RS two-dimensional code according to the present invention can be successfully restored only through RS decoding without LDPC decoding in a very high SNR environment (reception near the transmitter). For example, when 160 1 blocks are received as shown in FIG. 13, the receiving apparatus can decode 3 RS codewords out of 3.75 RS codewords. Therefore, the receiving apparatus can perform the RS decoding only without LDPC decoding in an environment with a very high SNR (for example, in the vicinity of the transmitter), thereby restoring information with minimum complexity and latency.

14 is a block diagram showing a transmitting apparatus for transmitting a codeword encoded with an LDPC-RS two-dimensional code according to an embodiment of the present invention.

Referring to FIG. 14, a transmitter 1400 for transmitting a terrestrial cloud broadcast signal according to the present invention may include an encoder 1410 and an output unit 1420.

The encoding unit 1410 encodes information to be transmitted into a two-dimensional code composed of an LDPC code and an RS code. The two-dimensional code may be a code whose row corresponds to the RS code and whose column corresponds to the LDPC code, and the LDPC code may be a QC-LDPC code. For example, the encoder 1410 may encode information to be transmitted primarily on a row-by-row basis using the RS code and encode the information on a column-by-column basis using the LDPC code. The coded information can be divided into a plurality of blocks based on the size of the cyclic permutation matrix constituting the LDPC code.

The output unit 1420 outputs information encoded by the encoding unit 1410 on a row-by-row basis. The output unit 1420 may output the information divided into a plurality of blocks on a block-by-block basis or on a bit-by-bit basis.

The information encoded by the LDPC-RS two-dimensional code by the transmitting apparatus 1400 is successfully restored by the partial decoding using the information constituting the LDPC codeword and a partial parity when the signal-to-noise ratio for the received signal is equal to or larger than the first threshold If the signal-to-noise ratio for the received signal is equal to or greater than the second threshold value, it can be successfully recovered only by RS decoding without LDPC decoding. In addition, it can be successfully decoded in a region (edge of a broadcast zone) where the signal-to-noise ratio of the received signal is low through complete decoding.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

Claims

A method for transmitting a terrestrial cloud broadcast signal,
Encoding information to be transmitted into a two-dimensional code composed of an LDPC (Low Density Parity Check) code and an RS (Reed-Solomon) code; And
And outputting the information encoded in the two-dimensional code on a row-by-row basis
.

The method according to claim 1,
The two-
Wherein a row corresponds to the RS code and a column corresponds to the LDPC code.

The method according to claim 1,
The LDPC code includes:
And a QC (Quasi-Cyclic) structure LDPC code.

The method according to claim 1,
The LDPC code includes:
A matrix of size g × K, a B matrix of size g × g, a C matrix of size (NKg) × (K + g), a D matrix of size (NKg) × (NKg) (NKg), < / RTI >
Wherein N represents a length of a codeword, K represents a length of information, and g represents a value varying in accordance with a coding rate.

The method according to claim 1,
Wherein the encoding comprises:
Wherein the information to be transmitted is encoded in units of rows using the RS code, and the information is encoded in units of columns using the LDPC code.

The method according to claim 1,
After the encoding step,
And dividing the information encoded by the two-dimensional code into a plurality of blocks based on a size of a cyclic permutation matrix constituting the LDPC code.

The method according to claim 6,
Wherein the outputting step comprises:
And outputting information divided into the plurality of blocks in block units.

The method according to claim 6,
Wherein the outputting step comprises:
And outputting information divided into the plurality of blocks in units of bits.

The method according to claim 1,
The information encoded by the two-
Wherein when the signal-to-noise ratio for the received signal is equal to or greater than the first threshold, the information is reconstructed by partial decoding using information constituting the LDPC codeword and a partial parity.

The method according to claim 1,
The information encoded by the two-
Wherein when the signal-to-noise ratio for the received signal is equal to or greater than the second threshold, the signal is recovered only by RS decoding without LDPC decoding.

A transmitting apparatus for transmitting a terrestrial cloud broadcast signal,
An encoder for encoding information to be transmitted into a two-dimensional code composed of an LDPC (Low Density Parity Check) code and an RS (Reed-Solomon) code; And
An output unit for outputting the information encoded by the two-
.

12. The method of claim 11,
The two-
Wherein a row corresponds to the RS code and a column corresponds to the LDPC code.

12. The method of claim 11,
The LDPC code includes:
And a QC (Quasi-Cyclic) structure LDPC code.

12. The method of claim 11,
The LDPC code includes:
A matrix of size g × K, a B matrix of size g × g, a C matrix of size (NKg) × (K + g), a D matrix of size (NKg) × (NKg) (NKg), < / RTI >
Wherein N represents a length of a codeword, K represents a length of information, and g represents a value varying in accordance with a coding rate.

12. The method of claim 11,
Wherein the encoding unit comprises:
Wherein the information to be transmitted is encoded in units of rows using the RS code and encoded in units of columns using the LDPC code.

12. The method of claim 11,
Wherein the encoding unit comprises:
And the information encoded by the two-dimensional code is divided into a plurality of blocks based on a size of a cyclic permutation matrix constituting the LDPC code.

17. The method of claim 16,
The output unit includes:
And outputs information divided into the plurality of blocks on a block-by-block basis.

17. The method of claim 16,
The output unit includes:
And outputs information divided into the plurality of blocks in bit units.

12. The method of claim 11,
The information encoded by the two-
When the signal-to-noise ratio for the received signal is equal to or greater than the first threshold, the information is reconstructed by partial decoding using information constituting the LDPC codeword and a partial parity.

12. The method of claim 11,
The information encoded by the two-
To-noise ratio of the received signal is equal to or greater than a second threshold, the signal is recovered only by RS decoding without LDPC decoding.