KR20130024704A - Method and apparatus transmitting and receiving information in broadcasting/communication system - Google Patents

Abstract

PURPOSE: An information transmission and reception method in a broadcasting or communication system and a device thereof are provided to maintain the stability of a system by maintaining a similar performance regardless of the length of a data word by adaptively selecting a contraction or perforation ratio according to channel state data required in the broadcasting or communication system. CONSTITUTION: The number of input information bits including signaling information for transmission is determined(600). A transmission end confirms parameters for calculating the length of a perforation bit(602). The number of parity bits based on the determined parameters is calculated(604). Parity bits are perforated for a code word based on the length of the calculated perforation parity bit(606). [Reference numerals] (600) Confirming the number of input information bits; (602) Confirming parameters for calculating the number of perforation bits; (604) Calculating the number of parity bits to be perforated using the parameters; (606) Perforating the parity bits; (AA) Start; (BB) End

Description

METHOD AND APPARATUS TRANSMITTING AND RECEIVING INFORMATION IN BROADCASTING / COMMUNICATION SYSTEM}

The present invention relates to the transmission and reception of information in a broadcasting / communication system, and more particularly, to a method and apparatus for controlling a code rate according to transmission and reception of signaling information in a broadcasting / communication system.

In a broadcast / communication system, link performance may be degraded due to noise, fading, and inter-symbol interference (ISI). Accordingly, it is essential to develop a technique for overcoming noise, fading and ISI in order to implement high speed digital broadcasting / communication systems requiring high data throughput and reliability. As part of this research, researches on error-correcting codes to improve the reliability of broadcasting / communication by efficiently restoring information distortion have been actively conducted. For example, the error correction code includes a Low Density Parity Check (LDPC) code.

The LDPC encoder (Encoder) is K _ldpc of bits in LDPC information bits consisting of (LDPC information bits, or LDPC information word, LDPC uncoded block) the input received LDPC encoded bits consisting of N _ldpc bits (LDPC coded bits, or LDPC codeword, LDPC codeword, LDPC coded block). When the input information bits (or input information words) length K _{sig that} are to be encoded are smaller than the LDPC information bit length K _ldpc input to the LDPC encoder, the transmitting end undergoes a shortening process. Encode In addition, when the number of parity bits (ie, parity bit length) N _{tx_parity} required by the transmitting end is smaller than the parity bit length (N _parity = N _ldpc -K _ldpc ) output from the encoder, the transmitting end is output from the encoder. _Punch the parity bits as much as (N _parity -N _{tx_parity} ).

If the shortening bit length is increased, the code rate is lowered, so that the BER / FER (Bit Error Rate / Frame Error Rate) performance of the code may be better than the code before shortening. On the other hand, when the bit length to be punctured increases, the code rate is increased, so that the BER / FER performance may be degraded than the code before puncturing. Accordingly, a technique of selecting an appropriate number of puncturing bits according to the length of the information word is required to maintain similar performance regardless of the length of the information word for the stability of the system.

The present invention provides a method and apparatus for transmitting and receiving information in a broadcasting / communication system.

The present invention provides a method and apparatus for controlling a code rate in a broadcast / communication system.

The present invention provides a method and apparatus for selecting a shortening / punching ratio according to the length of an information word in a broadcasting / communication system.

The present invention provides a method and apparatus for determining the number of bits to be punctured according to a length of an input information word in a broadcast / communication system.

A method according to a preferred embodiment of the present invention comprises: A method for transmitting information in a broadcast / communication system,

Comparing the number of bits of the information word to be transmitted with a predetermined threshold value; determining the first parameter pair when the number of bits of the information word is smaller than the threshold value; If not less than a threshold, determining a second parameter pair, determining the number of bits to puncture using any one of the first and second parameter pairs, and using the number of bits to puncture The method includes puncturing parity bits among codewords generated by encoding the information word.

Apparatus according to a preferred embodiment of the present invention; An apparatus for transmitting information in a broadcasting / communication system,

An encoder that encodes the information word to be transmitted and outputs a code word, and compares the number of bits of the information word with a predetermined threshold value to determine a first parameter pair when the number of bits of the information word is smaller than the threshold value; A controller for determining a second parameter pair when the number of bits of the information word is not less than the threshold value, and determining the number of bits to be punctured using any one of the first and second parameter pairs; And a puncturer for puncturing parity bits of the codeword by using the number of bits to be performed.

Method according to another embodiment of the present invention, in a method for receiving information in a broadcast / communication system,

Comparing the number of bits of the information word transmitted by the transmitter with a predetermined threshold value; determining the first parameter pair when the number of bits of the information word is smaller than the threshold value; When the number of bits is not smaller than the threshold, determining a second parameter pair, determining the number of bits to be punctured using any one of the first and second parameter pairs, and Generating a decoder input by generating corresponding values of bits punctured by the transmitting end by using the number of bits, inserting the generated values into a demodulated signal from a received signal, and decoding the decoder input by Restoring information word bits.

Apparatus according to another embodiment of the present invention, in the apparatus for receiving information in a broadcast / communication system,

A demodulator for demodulating a received signal, obtaining information about the number of bits of the information word transmitted by the transmitter, and comparing the number of bits of the information word with a predetermined threshold value, wherein the number of bits of the information word is the threshold; The first parameter pair is determined when the value is smaller than the value, and the second parameter pair is determined when the number of bits of the information word is not smaller than the threshold value. A controller for determining the number of bits to be transmitted, a puncturing processor for generating values corresponding to bits punctured by the transmitter using the number of bits to be punctured, and inserting the generated values into an output signal of the demodulator. And a decoder that receives the output values of the puncturing processor and decodes the information word bits.

According to the disclosed embodiment of the present invention, by selecting the shortening / puncturing ratio adaptively according to the channel state information required in the broadcasting / communication system, it is possible to maintain the stability of the system by maintaining similar performance regardless of the length of the information word have.

1 is a view showing a change in code rate according to an embodiment of the present invention;
2 and 3 are diagrams illustrating the efficiency of an LDPC code according to an embodiment of the present invention;
4 is a diagram illustrating a change in an effective code rate according to another embodiment of the present invention;
5 is a diagram illustrating the efficiency of an LDPC code according to another embodiment of the present invention;
6 is a diagram illustrating a procedure for puncturing parity bits according to an information bit length according to an embodiment of the present invention;
7 is a diagram illustrating a frame configuration for transmitting two types of parity bits according to an embodiment of the present invention;
8 illustrates a structure of an LDPC code for supporting transmission of parity bits according to another embodiment of the present invention;
9 is a diagram illustrating a change in an effective code rate according to another embodiment of the present invention;
10 is a diagram illustrating a procedure for determining the number of two types of parity bits according to an embodiment of the present invention; and
11 is a diagram illustrating a configuration of a transmitting end according to an embodiment of the present invention.
12 is a diagram illustrating a configuration of a receiving end according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intentions or customs of the user, the operator, and the like. Therefore, the definition should be based on the contents throughout this specification.

Hereinafter, a technique for controlling a code rate according to transmission and reception of data and information in a broadcasting / communication system will be described. The following description is based on the European Digital Broadcasting Standard DVB-T2 (Digital Video Broadcasting the 2nd Generation Terrestrial) system and the currently standardized Digital Video Broadcasting Next Generation Handheld (DVB-NGH) system. However, the same can be applied to other systems. In addition, the following description is assumed to control the code rate according to the transmission of the signaling information (signaling information), but may be equally applicable to the case of transmitting other information.

LDPC encoder in the transmission terminal of a broadcast / communication system is configured to output the _ldpc N (= K + N _{ldpc parity)} of LDPC coded bits to generate N _parity parity bits receives input of the K _ldpc LDPC information bits. Hereinafter, for the convenience of description, the input and output of the bits will be mentioned, but the same description is also applicable to the symbols.

Signaling bits among the input information bits that may be input to the encoder have a variable length. When signaling bits of variable length are input, the transmitting end may perform shortening and / or puncturing (hereinafter, referred to as shortening / punching). That is, if the length of the LDPC information bits of the LDPC encoder is K _ldpc , and signaling bits having a bit length of K _sig are input to the LDPC encoder, the bits of K _ldpc -K _sig are shortened. Herein, shortening means LDPC encoding by padding (K _ldpc -K _sig ) '0' bits to the signaling bits, and after LDPC encoding, deletes the padded '0' bits, or shortens through the padding and erasing. This means that the encoding is performed by reducing the size of the parity check matrix of the LDPC encoder having the same effect. The puncturing means excluding some of the encoded bits, in particular parity bits, from the transmission. As an example, the meaning that a bit is punched may indicate that the bit is not transmitted in the same frame as the input information bits.

As another example, two encoders may be connected to each other in a transmitting end of a broadcasting / communication system. As an example, an encoder concatenating a BCH code and an LDPC code is referred to as a BCH / LDPC (Bose, Chaudhuri, Hocquenghem / Low Density Parity Check) coder. In this case, the BCH encoder receives BCH information or information bits consisting of K _bch bits and receives BCH coding bits consisting of N _bch bits (BCH coded bits or BCH codeword or BCH coded block). Outputs N _bch is equal to the number of LDPC information bits (K _ldpc), and is sometimes called the LDPC information bits, which means that the information input to the LDPC encoder (LDPC information bits or a LDPC uncoded block). The BCH coded bits, that is, LDPC information bits, are input to the LDPC coder and output as LDPC coded bits, LDPC coded blocks, or LDPC codewords having a length of _Nldpc .

As mentioned above, among the information words input to the encoder, the signaling bits have a variable length. In this case, the transmitting end performs shortening / puncturing on the codeword output from the encoder. That is, signaling bits having a bit length of K _sig are input to the BCH / LDPC coder, and bits of K _bch -K _sig are shortened. In this case, the shortening means that the '0' bits (K _bch -K _sig ) of the input signaling bits are padded and BCH / LDPC encoded, and then the padded '0' bits are deleted.

As mentioned above, since shortening has an effect of lowering a code rate, encoding performance is improved as the number of bits to be shortened (that is, shortened bit length) increases. However, when encoding signaling information, it is preferable that a difference in encoding performance does not occur according to the length of input information. That is, when the reception power is constant in the receiver, there is no difference in performance depending on the length of the input information word. Therefore, by adjusting the number of bits to be punctured (ie, puncturing bit length) according to the number of shortened bits, stability of encoding performance can be obtained. The number of shortened bits is determined according to the bit length of the input information word, that is, the number of bits of the input information word. Consequently, the number of puncturing bits depends on the number of bits of the input information word.

_Hereinafter , embodiments for determining N _punc which is an input parameter used for the puncturing operation, that is, the number of bits to be punctured will be described.

As an embodiment, N _punc may be calculated by one of Equations 1 to 4 below.

Equations 1 and 2 may be used for the case where the BCH code is concatenated and the case where the BCH code is not concatenated. That is, since the number of bits shortened when concatenating a BCH code is (K _bch -K _sig ), N _punc can be obtained as in Equation 1 below.

In addition, since the number of bits shortened when the BCH code is not concatenated is (K _ldpc -K _sig ), N _punc can be obtained as in Equation 2 below.

는 바닥(floor) 함수를 의미하며, x보다 작거나 같은 최대의 정수를 의미한다. Here, A represents the ratio of the number of bits to be punctured compared to the shortened bits, and K _bch -K _sig and K _ldpc -K _sig mean the number of bits that are shortened. K _bch represents the number of BCH information bits (ie, information bit length) input to generate BCH coded bits composed of K _ldpc bits through BCH encoding, and K _ldpc indicates LDPC coded bits. The number of bits of the LDPC information input to generate, K _sig represents the bit length of the input information word before the shortened input to the encoder, B represents a correction factor. Also

Is the floor function, which is the largest integer less than or equal to x.

When the number of bits to be punctured is obtained based on Equation 1 or Equation 2, a code rate lower than that of the code rate without shortening and puncturing may be configured. It goes without saying that B can be omitted when B becomes zero.

As another embodiment, when N _punc is obtained based on Equation 3 or Equation 4 _below , a higher code rate than a code rate when no puncturing and puncturing is performed may be configured.

When concatenating the BCH code, so the number of bits to be shortened is K _bch -K _sig N _punc can be obtained as shown in the following <Equation 3>.

When not connecting and the BCH code, so the number of bits to be shortened is _ldpc -K K _sig N _punc can be obtained as shown in the following <Equation 4>.

Here, A represents the ratio of bits to be punctured compared to bits that are shortened, and K _bch -K _sig and K _ldpc -K _sig mean the number of bits shortened. K _bch represents the number of BCH information bits (that is, information bit length) input to generate BCH coded bits composed of K _ldpc bits through BCH encoding, and K _ldpc is LDPC input to generate an LDPC codeword. K _sig represents the number of bits of the input information word before being shortened to the encoder, and B represents a correction factor. K _{sig_min} represents the bit length of the shortest information word among information words that can be input to the encoder.

<Equation 3 and 4> In the B <N _parity -A is N _punc conditions must be satisfied in (K -K _{sig_min ldpc)} number of parity bits is smaller than N _parity.

In Equations 1 to 4, N _punc may be changed according to values of parameters A and B. That is, the code rate may vary according to the values of A and B. In the case of receiving K _ldpc bits and outputting N _ldpc coded bits, the code rate of the LDPC code is expressed by Equation 5 below.

For the input K _sig information word bits, the effective code rate after shortening and puncturing is expressed by Equation 6 below.

N _{bch_parity} is 0 when the BCH code is not used as the number of parity bits of the BCH code.

The effective code rate depends on A and B in <Equation 1> to <Equation 4>. The change in code rate will now be described with reference to FIGS.

1 illustrates a change in the effective code rate according to an embodiment of the present invention. FIG. 1 illustrates a case where A = 1.35 and B = 3320 are applied to Equation 3 when K _bch = 2100, K _ldpc = 2160, and N _ldpc = 8640, and A = 1.32 and B = 3320. The code rate change when applied to 3> is shown. As shown in FIG. 3, the code rate for transmitting information varies according to the change of A when applied to Equation 3. In particular, the larger A, the higher the code rate.

FIG. 2 shows the frame error rate (FER) of codewords for various information bit lengths, 280, 396, 880, 1350, 1550, 1670, 1900 when A = 1.35, B = 3320.

As shown, when the number of input information bits K _sig is 280, it can be seen that performance degradation occurs. Therefore, when FER = 10e-4, it can be seen that a difference of 0.7 dB occurs between the best performance and the poor performance.

FIG. 3 illustrates a frame error rate (FER) of codewords for various input information bit lengths, 280, 396, 880, 1350, 1550, 1670, and 1900 when A = 1.32 and B = 3320.

As shown in FIG. 2, since the coding rate is low, the overall performance is improved. In particular, when the number of input information bits K _sig is 1350, it can be seen that the performance is very good compared to other cases. In addition, it can be seen that the performance difference is about 0.7dB when FER = 10e-4 in case of the best performance and bad performance.

As mentioned above, it is preferable that the encoding performance according to the input information bit length does not occur much. Therefore, there is a need for a method of changing A and B values of Equations 1 to 4 according to the input information bit lengths.

Therefore, in the embodiment of the present invention, N _punc is determined as in Equation 7,8.

As described above, different values of A and B, namely A ₁ and B ₁ or A ₂ and B _2, are used depending on the input information bit length.

In the embodiment of Equation 7,8, the case in which the input information bit length is small and the case in which the input information bit length is large is distinguished based on one predetermined threshold value K _th . Of course, more than two pairs of values of A and B can be used.

As an embodiment, K _th may be determined experimentally so that a difference in encoding performance according to N _punc does not occur. In particular, it is determined by a value that shows relatively good performance or relatively poor performance compared to other values. Also, different parameter pairs (A ₁ , B ₁ ) and (A ₂ , B ₂ ) are determined such that the N _punc value is the same when K _sig = K _th .

As described above, the number of puncturing bits is preferably adjusted according to the number of shortening bits, and the number of shortening bits is determined according to the bit length of the input information word. Therefore, A ₁ and A ₂ representing the ratio of the number of punctured bits to the shortened bits may be constant values determined according to the bit length of the input information word. Accordingly, B ₁ and B ₂ can also be set to constant values.

When N _punc is determined as described above, the transmitter performs puncturing on the parity bits among the coded bits generated by encoding the input information bits using N _punc .

4 is a diagram illustrating a change in the effective code rate according to an embodiment of the present invention, in which A = 1.35 and B = 3320 are applied to Equation 3, and A = 1.32 and B = 3320 3 is shown in comparison with the case where Equation 7,8 is used (shown as "proposed"). "proposed" is A ₁ = 1.3, B ₁ = 3357, A ₂ = 1.35, B ₂ = 3320, and K _th = 1350 for K _bch = 2100, K _ldpc = 2160, N _ldpc = 8640 In the case of applying to>, it can be seen that the same code rate as in the case of applying A = 1.35 and B = 3320 to Equation 3 when K _sig is equal to K _th is equal to or greater than 1350.

FIG. 5 is a diagram illustrating an FER according to an embodiment of the present invention and shows FER performance for various information bit lengths 280, 396, 880, 1350, 1550, 1670, and 1900. As shown in the figure, when the input information bit length is 280, it can be seen that the performance is better because the code rate is low compared to the embodiment shown in FIG. In addition, when the input information bit length is 1350, since the code rate is higher than that of the embodiment shown in FIG. 3, it can be seen that performance degradation occurs. Therefore, the overall performance difference is 0.3 dB, which reduces the difference in encoding performance compared to FIGS.

In the above, an embodiment of obtaining N _punc which is the number of bits to be punctured using the above equations has been described. While the following description for the embodiment the value obtained using the above equation as a temporary value of N _punc, i.e. temporary drilling bit number (N _{punc_temp)} and, more precisely via a number of processes to obtain the N _punc. In an embodiment to be described later, in performing a puncturing operation using N _punc , the transmitter may additionally precisely adjust N _punc according to additional parameters, for example, the number of BCH parity bits, a modulation order, and the like. It will be described the procedure for calculating the N _punc indicating the number of last bits to be punctured by using the following N _{punc_temp.}

Stage 1:

The number of temporary puncturing bits N _{punc_temp} is calculated through Equation 7 described below and Equation 9 below, which is substantially the same as the description related to the above equation.

In the present embodiment, an LDPC code concatenated with a BCH code is used, and in Equation 9, values (A ₁ , B ₁ ) = (1.3, 3357) and (A ₂ , B), which are values presented through the description of FIG. An example in the case of ₂ ) = (1.35, 3320) was described.

Step 2:

The number of temporary encoded bits N _{post_temp} using N _{punc_temp} is calculated by Equation 10 below.

Here, K _sig is the number of input information bits as described above and may be, for example, the number of signaling information bits. N _{bch_parity} represents the number of BCH parity bits, and N _{ldpc_parity_ext_4K} is a constant value determined according to the type of LPDC code. As an example, when extended 4K LDPC is used, N _{ldpc_parity_ext_4K} is 6480.

STEP 3:

In consideration of N _{post_temp} and a modulation order, the final coded bit number (bit number of each LDPC block) is calculated as in Equation 11 below.

Where η _MOD is the modulation order, 1, 2 for Binary Phase Shift Keying (BPSK), Quadrature PSK (QPSK), 16-ary Quadrature amplitude modulation (16-QAM), and 64-QAM (64-ary QAM), respectively. , 4, 6.

The reason for determining the number of bits N _{post in} which each information word block is encoded as in the above equation is to make N _post a multiple of the number of columns of the block interleaver. Although the block interleaver is not shown or further described, the bits of each LDPC block are used in a process of later bit interleaving.

When the block interleaver is not used, for example, when only BPSK and QPSK are used, Equation 11 may be changed to the following equation.

STEP 4:

Finally, N _punc representing the number of bits to be punctured among the parity bits of each LDPC block is calculated as shown in Equation 12 below.

6 is a flowchart illustrating a procedure for puncturing parity bits according to an input information bit length according to an embodiment of the present invention.

Referring to FIG. 6, the number of input information bits (ie, input information bit length) including signaling information for transmission in operation 600 is determined. In step 602, the transmitter checks the number of bits to be punctured, that is, parameters for calculating the puncturing bit length. That is, as mentioned in Equations 7 to 8, it is determined whether A ₁ , B ₁ or A ₂ , B ₂ is selected according to the input information bit length. Although not shown, it is also possible to select one of two or more predetermined parameter pairs depending on the input information bit length. In another embodiment, in step 602, the transmitter determines the parameter values (A ₁ , B ₁ ) = (1.3, 3357) to be used in Equation 9 according to a result of comparing the input information bit length with a predetermined threshold value 1350. (A ₂ , B ₂ ) = (1.35, 3320) is obtained.

In operation 604, the number of parity bits to be punctured (ie, puncturing parity bit length) is calculated based on the determined parameters. In operation 604, the number of parity bits to be punctured may be determined as in Equations 7 and 8, or may be determined by Equations 9 to 12. In step 606, the puncturing of the parity bits for the codeword is performed based on the calculated puncturing parity bit length.

Meanwhile, parity bits generated for the signaling bits, which are the input information bits, may be transmitted by being divided into the same frame and the earlier frame as the frame in which the signaling bits are transmitted. In this case, parity bits transmitted through the same frame as the signaling bits are referred to as first parity and parity bits transmitted through a previous frame as second parity or additional parity.

7 illustrates a frame configuration for transmitting two types of parity bits according to an embodiment of the present invention.

As shown, Layer 1 signaling bits are transmitted on the (i) th frame 702, and the first parity 710 generated for the signaling bits is (i) th frame along with the signaling bits. The additional parity 712 is transmitted through the (i-1) th frame 700.

In one embodiment, the receiving end decodes based on the first parity and the signaling bits received through the (i) th frame 702. If decoding fails, the receiving end performs decoding using up to the additional parity 712 received through the (i-1) th frame 700. In another embodiment, when decoding of the signaling bits and the first parity fails, the receiving end determines that the decoding of the signaling bits has failed and stores the additional parity included in the (i) th frame 702 (i + 1) Receive the first frame. In another embodiment, the receiving end always stores additional parity received through the (i-1) th frame 700, and receives the first parity and the signaling bits received through the (i) th frame 702. Decryption is performed based on the stored additional parity.

As described above, when the receiver decodes input information bits, a method of determining the number of additional parity bits is required. Hereinafter, a method of determining the number of additional parity bits will be described in detail.

As an embodiment, the number of additional parity bits may be expressed as Equation 13 below.

Α · I _l in Equation 13 Denotes the ratio of the number of first parity bits to the number of additional parity bits. Where α is a fixed value and I _i Can be selected from 0 to L-1 value and represents L1 additional parity ratio. I _i may be transmitted through a separate signaling called 'L1_AP_RATIO'. I _i 0 means that no additional parity bits are used. N _{tx _ parity} means the number of parity bits (ie, first parity bits) transmitted in the same frame as the information word, and in other words, the number of parity bits actually transmitted. In this case, it may be calculated as N _{tx_parity} = N _parity -N _punc .

Hereinafter, a specific embodiment for determining the number of parity bits to be punctured and the number of additional parity will be described.

8 is a diagram illustrating an example of a structure of an LDPC code for supporting parity transmission.

As shown, the LDPC codeword is _composed of K _ldpc LDPC information bits 800, N _parity bits, and M _IR incremental redundancy (IR) parity bits. For convenience, N _parity bits 802 and M _IR incremental redundancy (IR) parity bits 804 may be collectively referred to as 'parity bits'. The structure of the LDPC code of FIG. 8 is designed by considering the parity bit 802 first when designing the LDPC code. Therefore, the IR parity bits 804 are preferentially punctured during puncturing. In addition, the LDPC code of FIG. 8 may be expressed as parity bits without distinguishing the parity bits 802 and the IR parity bits 804.

In order to encode the signaling bits 806, the LDPC information bits 800 of FIG. 8 are divided into signaling bits 806 and parity bits 807 of the BCH code and '0' padding bits 808 for shortening. Parity bits 802 and IR parity bits 804 are composed of non-perforated parity bits 810 and perforated parity bits 812. The specific position (i.e., index) of each bit here is not related to the main subject matter of the present invention and thus will not be described in this document. That is, specifically, which of the parity bits 802 and the IR parity bits 804 are punctured and which bits are not punctured, i.e., no puncturing pattern is mentioned. Also not to mention which bits in the LDPC information bits 800 are signaling bits 806, which bits are zero padding 808, which bits are BCH parity bits 807, and the location of each bit. do. In addition, the parity bits 807 of the BCH code exist when the concatenated codes of the BCH code and the LDPC code exist, and the BCH parity bits 807 are omitted when only the LDPC code is used.

The signaling bits 806, the BCH parity bits 807, and the non-perforated parity bits 810 constitute the first part 814 and are transmitted in the (i) th frame 702 of FIG. 7. In addition, some of the punctured parity bits 812 constitute an additional parity 816 and are transmitted in the (i-1) th frame 700 of FIG. 7. That is, some of the punctured parity bits 812 are the same as the additional parity 708, 712 of FIG. 7. The specific way of configuring the additional parity 708 can vary. For example, the punctured parity bits 812 may be preferentially selected as additional parity.

Hereinafter, a specific example using the transmission method of FIG. 8 will be presented.

For K _bch = 2100, K _ldpc = 2160, N _ldpc = 4320, M _IR = 4320, R _ldpc = K _ldpc / N _ldpc = 1/2, R _IR = K _ldpc / (N _ldpc + M _ldpc ) = 1 / 4. In this case, N _punc may be obtained as in Equation 14 based on Equation 7 according to an embodiment.

Equation (14) represents A ₁ = 1.3, B ₁ = 3357, A ₂ = 1.35, B ₂ = 3320, and K _th = 1350. Therefore, N _punc parity bits according to Equation 14 are punctured among the parity bits 802 and the IR parity bits 804 of FIG. 8. Or may in other embodiments <Equation 9> N _punc parity bits obtained with <Equation 10 to 12> on the basis of the N _{punc_temp} may be perforated.

It is _apparent that specific values of parameters used to _obtain N _punc may be determined according to the modulation scheme used for transmission and the number of orthogonal frequency division multiplexing (OFDM) symbols. For example, when 2 ⁿ -QAM (Quadrature Amplitude Modulation) is used as a modulation method, the number of transmitted bits (K _sig + N _{bch_parity} + N _parity + M _IR -N _punc ) becomes a multiple of n. Here, K _sig denotes the number of input signaling information bits, N _{bch _ parity} denotes the number of parity bits of the BCH code, and n denotes the order of the modulation scheme.

In addition, the number of bits of the additional parity 712 of FIG. 7 or the additional parity 816 of FIG. 8 may be obtained as in Equation 15 below.

where I ₀ = 0, I ₁ = 1, I ₂ = 2, I ₃ = 3

Equation 15 applies α = 0.35 to Equation 13, and α is a value selected to satisfy Equation 16 below.

That is, α is the number of first parity bits (N _{tx_parity} ) and additional parity transmitted when I _l is the maximum value I _L-1 and K _sig is the longest length K _{sig_max} among the input information bits that can be input. the maximum sum (N + N _{tx_parity add_parity)} of the number of bits (N _{add_parity)} of and, and the sum is determined as the maximum value of the values to be a value smaller than the N + M _{parity IR.}

In the above embodiment, when the longest length of the input information bits K _{sig_max} = 2100, N _punc = 3320, N _{tx_parity} = 3160, and when I _l is the maximum value I _L-1 = I ₃ = 3 N _{Since add_parity} = 0.35 × 3 × 3160 = 3318, N _{tx _ parity} + N _{add _ parity} = 6478, which is smaller than N _parity + M _IR = 6480.

In the above, an embodiment of obtaining N _{add_parity} which is the number of additional parity bits using the above equations has been described. Hereinafter, an embodiment of obtaining more precise N _{add_parity} in consideration of a modulation scheme used for transmission based on N _{add_parity} , which is a value obtained using the above equations, will be described.

<Equation 16> assumes the case of using the BPSK modulation method. That is, when the BPSK modulation scheme is used, α is determined so that the number of first parity bits and the number of additional parity bits transmitted are smaller than N _parity + M _IR . Therefore, even when using other modulation schemes, for example, QPSK, 16-QAM, and 64-QAM, Nadd_parity needs to be corrected so that the number of first parity bits and the number of additional parity bits are smaller than N _parity + M _IR. Do. Therefore, the number of temporary additional parity bits can be obtained as in Equation 17 below.

K is the L1 additional parity ratio, which is another expression of I _i of Equations 13 and 15. As an embodiment, K may be delivered from the transmitter to the receiver through separate signaling called 'L1_AP_RATIO'. For example, 'L1_AP_RATIO' is a 2-bit parameter, K = 0 when the parameter is '00', K = 1 when the parameter is '01', K = 2 when the parameter is '10', and If the parameter is '11', it means K = 3.

In consideration of N _{add_parity_temp} of Equation 17 and a modulation order, the number of final additional parity bits is calculated as in Equation 18 below.

Where η _MOD indicates the modulation order, which is 1, 2, 4, 6 for BPSK, QPSK, 16-QAM, and 64-QAM, respectively.

The reason for adjusting the number of additional parity bits N _{add _ parity} as shown in Equation 18 is to make N _{add_parity} a multiple of the number of columns of the block interleaver. The block interleaver is used in the case where each additional parity bit is bit interleaved.

When the block interleaver is not used, for example, when only BPSK and QPSK are used, Equation 18 may be changed to the following Equation.

In addition, it is obvious that N _{add _ parity} may be determined according to the number of OFDM symbols used for transmission.

Information on the number of additional parity bits may be transmitted from the transmitter to the receiver through a signaling parameter called L1_AP_SIZE. If a plurality of LDPC coded blocks are used for transmission, L1_AP_SIZE indicates the product of the number of coded blocks and N _{add _ parity} . For example, when two coding blocks are used, 'L1_AP_SIZE' may indicate 2 × N _{add_parity} . The signaling parameter allows the receiver to know the number of additional parity bits.

FIG. 9 illustrates a code rate when the number of additional parity bits is calculated as shown in Equation 15. FIG. The code rate is calculated as in Equation 19 below.

Where N _{tx_parity;} means the number of parity bits of the part 814 of Fig. 8, in which the N + M _{ldpc IR punc} -N = N-6480 _punc. N _{add_parity} means additional parity bits of the 816 part of FIG. 8.

In FIG. 9, AP (Additional Parity) = 0 represents a code rate when no additional parity is used as I ₀ = 0. AP = 1 in FIG. 9 is I ₁ = 1 and AP = 2 is In the case of I ₂ = 2, AP = 3 means the code rate in the case of I ₃ = 3.

In another embodiment of the present invention, IR parity bits 804 may optionally be used in the LDPC code of FIG. That is, only parity bits 802 may be generated first with respect to input information word bits, and IR parity bits 804 may be generated only when IR parity is required. This is a method for increasing the encoding / decoding efficiency.

As mentioned above, only the parity bits 802 are preferentially generated for the input information bits, and N _punc is generated for the parity bits 802 based on Equation 7 according to an embodiment. It can be obtained as shown in Equation 20.

If N _punc is positive in Equation 20, only the parity bits 802 are generated, and then punctures N _punc parity bits only for the parity bits 802. On the other hand, when N _punc is negative, after generating both parity bits 802 and IR parity bits 804, only the IR parity bits 804 are punctured by M _IR + N _punc . Alternatively, parity bits of N _{punc, which} are obtained by using Equations 10 to 12 based on Equation 20, are punctured.

10 illustrates a procedure for determining the number of two types of parity bits according to an embodiment of the present invention.

Referring to FIG. 10, in step 1000, the number of parity bits to be punctured is calculated using Equations 7,8 and 9 through 12. In step 1002, parameters α, I ₁ , and N _{tx_parity} for use in Equations 13, 15, and 17 are determined. In addition, α or I ₁ , which has been determined in step 1002, can be used, and I ₁ , is expressed as K in Equation 17,18. As mentioned above, K may be indicated by a separate signaling called 'L1_AP_RATIO'. In step 1004, the number of additional parity bits (ie, additional parity bit length) N _{add_parity} is determined based on Equation 13 or Equation 17,18 using the determined parameters. In step 1006, additional parity bits are configured according to the calculated number of additional parity bits.

11 is a block diagram of a transmitter according to an embodiment of the present invention.

Referring to FIG. 11, the transmitting end is an encoder 1101, a puncturer 1103, a controller 1105, a modulator 1107, and an RF (Radio Frequency) processor 1109 and optionally An additional parity configurator 1111.

The encoder 1101 outputs encoded bits generated by encoding information word bits for transmission. For example, BCH / if the LDPC code is used, the encoder 1101 to the BCH information bits consisting of K _bch BCH encoded bits to generate a BCH codeword consisting of K _ldpc bits. After that, the encoder 1101 LDPC-codes the BCH codeword to generate and output an LDPC codeword composed of N _ldpc bits. Alternatively, an LDPC codeword composed of (N _ldpc + M _IR ) bits is generated and output. Although not described in detail in the drawings BCH information bits consisting of K _bch bits are the K _sig of input information bits it can be configured by inserting (K _bch K _sig) of '0' bit. Also not shown, but (K _bch K _sig ) '0' padded bits are not transmitted.

The puncturer 1103 punctures the codeword provided from the encoder 1101 according to the puncturing pattern and puncturing bit length K _bch -K _sig provided from the controller 1105. The controller 1105 controls the puncturer 1103 by calculating the puncture bit length according to the number of information bits. For example, the controller 1105 determines the A value and the B value according to the number of input information bits (or the number of signaling bits) for transmission by the transmitter, as shown in FIG. 6, and provides them to the puncturer 1103. do. Or obtain the number of bits to be punctured from the determined parameters (A value and B value), and provide the obtained number of bits to be punctured to the puncturer 1103. The modulator 1007 receives a signal provided from the puncturer 1003. Modulate and output according to the modulation method. The RF processor 1009 converts the modulated signal provided from the modulator 1007 into a high frequency signal and transmits the same through an antenna.

In an alternative embodiment, when transmitting additional parity bits, the controller 1105 determines the number of additional parity bits and provides them to the additional parity configurator 1111 as shown in FIG. 10. The additional parity configurator 1111 configures additional parity bits and provides them to the modulator 1107. In this case, it should be noted that the additional parities generated in the current frame are transmitted in the previous frame.

In the above embodiment, when (N _ldpc , K _ldpc ) based on LDPC encoding, the (K _ldpc -K _sig ) bit is shortened with respect to the input information bit length K _sig . If the BCH code is concatenated, the (K _bch -K _sig ) bit is shortened with respect to the BCH information bit length K _bch .

12 illustrates a configuration of a receiving end according to an embodiment of the present invention.

Referring to FIG. 12, the receiving end includes an RF processor 1200, a demodulator 1202, a shortening / puncturing processor 1204, a decoder 1206, a controller 1208, and optionally an additional parity processor. 1210).

The RF processor 1200 receives a signal transmitted from the RF processor 1109 of the transmitting end and provides the signal to the demodulator 1202.

The demodulator 1202 demodulates the signal provided from the RF processor 1200 corresponding to the modulation scheme of the modulator 1107 of the transmitting end. As an example, the demodulator 1202 takes a logarithm of the probability that each bit is 1 and the probability that each bit is 1 and 0 for each of the shortened / punched coded bits and the additional parity bits transmitted through the modulator 1107. A Log Likely Ratio (LLR) value may be obtained and provided to the short / drill processor 1204 and the additional parity processor 1210. The additional parity processor 1210 is an optional embodiment and will not be used if no additional parity has been received.

The shortening / puncturing processor 1204 receives the output signal of the demodulator 1202, generates values corresponding to shortening and puncturing for bits shortened and punctured by the transmitting end, and outputs the output signals from the demodulator 1202. Insert it. For example, when the LLR value is obtained for the shortened bit, the maximum value is set to the (+) or (-) maximum value of the decoder input value, and the LLR value is set to '0' for the punctured bit. In this case, the shortening / punching processor 1204 receives information about the number of shortened and punctured bits and the index from the controller 1208. That is, the controller 1208 controls the shortening / punching processor 1204 by calculating the puncturing bit length according to the number of information bits of the encoder 1101 of the transmitting end. For example, the controller 1208 determines the A value and the B value according to the number of bits of the signaling information to be transmitted by the transmitter, as shown in FIG. 6, and provides the A / B value to the short / puncture processor 1204. Alternatively, the number of bits to be punctured is obtained from the determined parameters A value and B value, and the short / drill processor 1204 is provided. In this case, information about the number of input information bits input to the encoder of the transmitting end may be transmitted to the controller 1208 of the receiver through additional signaling as an example.

The decoder 1206 receives the output values of the shortening / puncturing processor 1204 and decodes the information word bits. For example, when a BCH / LDPC code is used, the decoder 1206 receives N _ldpc or (N _ldpc + M _IR ) LLR values and performs LDPC decoding to recover K _ldpc bits, and then performs BCH decoding. Restore K _bch information word bits through

In an alternative embodiment, when additional parity bits are transmitted, the controller 1208 determines the number of additional parity bits and provides them to the additional parity processor 1210 as shown in FIG. 10. The additional parity processor 1210 receives LLR values for additional parity bits generated by the transmitting end from the demodulator 1202 and provides the decoder 1206 to the decoder 1206, and the decoder 1206 is a shortening / punching processor 1204. Decryption is performed using both the values provided from and the values provided from the additional parity processor 1210. Note that the additional parities received in the current frame are used in the decoding process of the next frame according to processing at the transmitter. That is, when decoding the code received in the current frame, the additional parity bits received in the previous frame are used.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

Claims (24)

A method for transmitting information in a broadcast / communication system,
Comparing the number of bits of the information word to be transmitted with a predetermined threshold value;
Determining a first parameter pair when the number of bits of the information word is smaller than the threshold value;
Determining a second parameter pair when the number of bits of the information word is not smaller than the threshold value;
Determining the number of bits to be punctured using any one of the first and second parameter pairs;
Puncturing the parity bits of the codewords generated by encoding the information word using the number of bits to be punctured.
The method of claim 1, wherein the determining of the number of bits to be punctured comprises:
Calculating a temporary number of bits to be punctured using the first or second parameter pair;
Calculating a temporary number of encoded bits using the temporary number of bits to be punctured;
Calculating a final number of coded bits by using the temporary number of coded bits and a modulation order;
And finally determining the number of bits to be punctured by using the temporary number of bits to be punctured, the temporary number of the encoding bits, and the final number of the encoding bits.
The method of claim 2, wherein the temporary number of bits to be drilled,
Information transmission method characterized in that determined according to the following equation.

Here, N _{punc_temp} denotes the temporary number of the perforations to bits, K _bch denotes the input bit length of the BCH (Bose, Chaudhuri, Hocque-nghem) encoder, K _sig denotes the number of bits of the information word, (1.3 , 3357) is a first parameter pair, (1.35, 3320) is a second parameter pair, and the threshold is 1350.
The method of claim 1,
Determining at least one third parameter for determining an additional parity bit length,
Determining the additional parity bit length using the at least one third parameter;
And generating additional parity bits by encoding the information word using the additional parity bit length.
The method of claim 4, wherein the at least one third parameter,
And a ratio of the number of first parity bits and additional parity bits transmitted in the same frame as the information _word , and the number N _{tx_parity} of the first parity bits.
The method of claim 4, wherein the additional parity bit length is,
Information transmission method characterized in that determined according to the following equation.

Where η _MOD indicates modulation order, and is 1, 2, 4, and 6 for BPSK, QPSK, 16-QAM, and 64-QAM, respectively, and N _{add _ parity _ temp} is determined according to the following equation.

Where N _parity is the number of parity bits, N _punc is the number of bits to puncture, and K is an additional parity ratio.
An apparatus for transmitting information in a broadcasting / communication system,
An encoder which encodes an information word to be transmitted and outputs a code word,
By comparing the number of bits of the information word with a predetermined threshold value, if the number of bits of the information word is smaller than the threshold value, a first parameter pair is determined, and the number of bits of the information word is not smaller than the threshold value. A controller for determining a second parameter pair, and for determining the number of bits to be punctured using any one of the first and second parameter pairs;
And a puncturer for puncturing parity bits of the codeword by using the number of bits to be punctured.
8. The method of claim 7, wherein the controller determines the number of bits to puncture:
Using the first or second parameter pair, calculate a temporary number of bits to puncture,
Calculate a temporary number of encoded bits using the temporary number of bits to be punctured,
Calculate a final number of coded bits using the temporary number of coded bits and a modulation order,
And finally determining the number of bits to be punctured by using the temporary number of bits to be punctured, the temporary number of the encoding bits, and the final number of the encoding bits.
The method of claim 8, wherein the temporary number of bits to be drilled,
An information transmission apparatus, characterized in that determined according to the following equation.

Here, N _{punc_temp} denotes the temporary number of the perforations to bits, K _bch denotes the input bit length of the BCH (Bose, Chaudhuri, Hocque-nghem) encoder, K _sig denotes the number of bits of the information word, (1.3 , 3357) is a first parameter pair, (1.35, 3320) is a second parameter pair, and the threshold is 1350.
The method of claim 7, wherein the controller,
Determine at least one third parameter for determining an additional parity bit length, determine the additional parity bit length using the at least one third parameter, and encode the information word according to the additional parity bit length And control the encoder to generate additional parity bits.
The method of claim 10, wherein the at least one third parameter,
And at least one of a ratio of the number of first parity bits and additional parity bits transmitted in the same frame as the information _word , and the number N _{tx_parity} of the first parity bits.
The method of claim 10, wherein the additional parity bit length is,
An information transmission apparatus, characterized in that determined according to the following equation.

Where η _MOD indicates modulation order, and is 1, 2, 4, and 6 for BPSK, QPSK, 16-QAM, and 64-QAM, respectively, and N _{add _ parity _ temp} is determined according to the following equation.

Where N _parity is the number of parity bits, N _punc is the number of bits to puncture, and K is an additional parity ratio.
In the method for receiving information in a broadcast / communication system,
Comparing the number of bits of the information word transmitted by the transmitting end with a predetermined threshold value,
Determining a first parameter pair when the number of bits of the information word is smaller than the threshold value;
Determining a second parameter pair when the number of bits of the information word is not smaller than the threshold value;
Determining the number of bits to be punctured using any one of the first and second parameter pairs,
Using the number of bits to be punctured, generating corresponding values of bits punctured by a transmitting end, and inserting the generated values into a demodulated signal from a received signal to generate a decoder input;
And restoring information word bits by decoding the decoder input.
The method of claim 13, wherein the determining of the number of bits to be punctured comprises:
Calculating a temporary number of bits to be punctured using the first or second parameter pairs;
Calculating a temporary number of encoded bits using the temporary number of bits to be punctured;
Calculating a final number of coded bits by using the temporary number of coded bits and a modulation order;
And finally determining the number of punctured bits by using the temporary number of punctured bits, the temporary number of encoded bits, and the final number of encoded bits.
The method of claim 14, wherein the temporary number of bits to be punctured is:
Information transmission method characterized in that determined according to the following equation.

Here, N _{punc_temp} denotes the temporary number of bits that the puncturing, K _bch is BCH indicates the input bit length of (Bose, Chaudhuri, Hocque-nghem) encoder, K _sig denotes the number of bits of the information word, (1.3 , 3357) is a first parameter pair, (1.25, 3320) is a second parameter pair, and the threshold is 1350.
The method of claim 13,
Determining at least one third parameter for determining an additional parity bit length,
Determining the additional parity bit length using the at least one third parameter;
Using the additional parity bit length, generate corresponding values of bits additionally punctured by the transmitting end, and insert corresponding values of the generated additional punctured bits into a demodulated signal from a received signal to generate a decoder input. Information receiving method further comprises the step of.
The method of claim 16, wherein the at least one third parameter,
And a ratio of the number of first parity bits and additional parity bits transmitted in the same frame as the information _word , and the number N _{tx_parity} of the first parity bits.
The method of claim 16, wherein the additional parity bit length is
Information receiving method, characterized in that determined according to the following equation.

Where η _MOD indicates modulation order and is 1, 2, 4, 6 for BPSK, QPSK, 16-QAM, and 64-QAM, respectively, and N _{add _ parity _ temp} is determined according to the following equation.

Where N _parity is the number of parity bits, N _punc is the number of bits to puncture, and K is an additional parity ratio.
An apparatus for receiving information in a broadcasting / communication system,
A demodulator for demodulating a received signal,
Acquires information on the number of bits of the information word transmitted by the transmitter, compares the number of bits of the information word with a predetermined threshold value, and if the number of bits of the information word is smaller than the threshold value, a first parameter pair Determine a second parameter pair if the number of bits of the information word is not less than the threshold value, and determine a number of bits to be punctured using any one of the first and second parameter pairs. Wow,
A puncturing processor for generating values corresponding to the bits punctured by the transmitting end using the number of punctured bits and inserting the generated values into an output signal of the demodulator;
And a decoder which receives the output values of the puncturing processor and decodes the information word bits.
The method of claim 19, wherein the controller,
Calculate the temporary number of bits to be punctured using the first or second parameter pair,
Calculate a temporary number of encoded bits using the temporary number of bits to be punctured,
Calculate a final number of coded bits using the temporary number of coded bits and a modulation order,
And finally determining the number of bits to be punctured by using the temporary number of bits to be punctured, the temporary number of the encoding bits, and the final number of the encoding bits.
The method of claim 20, wherein the temporary number of bits to be punctured,
An information receiving apparatus, characterized in that determined according to the following equation.

Here, N _{punc_temp} denotes the temporary number of bits that the puncturing, K _bch is BCH indicates the input bit length of (Bose, Chaudhuri, Hocque-nghem) encoder, K _sig denotes the number of bits of the information word, (1.3 , 3357) is a first parameter pair, (1.25, 3320) is a second parameter pair, and the threshold is 1350.
The method of claim 19, wherein the controller,
Determining at least one third parameter for determining an additional parity bit length, determining the additional parity bit length using the at least one third parameter, and using the additional parity bit length, by the transmitting end And control the puncturing processor to generate corresponding decoders by generating corresponding values of the additional punctured bits generated in the demodulated signal from the received signal by generating corresponding values of the punctured bits.
The method of claim 22, wherein the at least one third variable,
And a ratio of the number of first parity bits and additional parity bits transmitted in the same frame as the information _word , and the number N _{tx_parity} of the first parity bits.
The method of claim 22, wherein the additional parity bit length is
An information receiving apparatus, characterized in that determined according to the following equation.

Where η _MOD indicates modulation order, and is 1, 2, 4, and 6 for BPSK, QPSK, 16-QAM, and 64-QAM, respectively, and N _{add _ parity _ temp} is determined according to the following equation.

Where N _parity is the number of parity bits, N _punc is the number of bits to puncture, and K is an additional parity ratio.

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