TWI513198B - Method and apparatus for transmitting and receiving control information in a broadcasting/communication system - Google Patents

Description

Method and device for transmitting and receiving control information in a broadcast/communication system

The present invention relates generally to methods and apparatus for transmitting and receiving control information in a broadcast/communication system, and more particularly to the use of Low Density Parity Check (LDPC) codes in broadcast/ A method and apparatus for transmitting and receiving control information in a communication system.

Figure 1 illustrates a frame for use in a conventional broadcast/communication system.

Referring to Figure 1, a frame 101 containing control information is transmitted and received in a broadcast/communication system. The frame 101 includes a preamble 102, a layer 1 (L1) signal 103, and a data 104. Herein, control information can be transmitted in the preamble 102 and the L1 signal 103. The preamble 102 is a signal for acquiring time and frequency synchronization of the receiver, frame boundary synchronization, and the like.

As illustrated in FIG. 1, the material 104 includes Physical Layer Pipes (PLP) 108, 109, and 110. Different modulation schemes and code rates can be used independently for PLP.

The L1 signal 103 indicates where the L1 signal is transmitted and includes the L1 pre-information 105, the L1 configurable information 106, and the L1 dynamic information 107. The L1 configurable information 106 and the L1 dynamic information 107 are referred to as L1 post signal information 120. In addition, the L1 configurable information 106 may be referred to as a configurable L1 post signal, and the L1 dynamic information 107 may be referred to as a dynamic L1 post signal.

The L1 pre-information 105 contains information that rarely changes in the time domain, such as community identifiers, network identifiers, the number of radio frequencies, the length of the frame, and the location of the pilot subcarriers. L1 configurable information 106 contains The L1 pre-information 105 changes the information more frequently. Examples of L1 configurable information 106 include a PLP identifier, a modulation scheme for transmitting each PLP, and code rate information.

In FIG. 1, the L1 dynamic information 107 contains information that may be changed in each frame, such as information on the location of the PLP for transmitting each service data in the current frame (ie, each of the transmission service data). Information about the position of a PLP at the beginning and end of the current frame).

In addition, the L1 post-signal information 120 may include information different from the L1 post-configurable information 106 and the dynamic information 107. For example, the L1 post-signal information 120 may include extended information, a Cyclic Redundancy Check (CRC), and an L1 padding. For example, the use of CRC has been described in "Peterson, WW and Brown, DT (January 1961). 'Cyclic Codes for Error Detection 'Proceedings of the IRE 49:228. doi:10.1109/JRPROC.1961.287814" .

PLP 1 108, PLP 2 109, and PLP N 110 are service profiles, each of which transmits at least one broadcast service channel. PLP 1 108, PLP 2 109, and PLP N 110 contain actual broadcast material.

Referring to FIG. 1, the receiver that has acquired the synchronization of the frame 101 from the preamble 102 obtains information including the scheme by which the data is transmitted, the length of the frame, and the like via the L1 signal information 103. The receiver then receives the relevant data via the PLPs 108-110 based on the obtained information.

As described above, when transmitting control information such as signal information in a broadcast/communication system, the coding efficiency of the control information must be better than the data information. The coding efficiency. Therefore, there is a need for an efficient coding method for signal information and an effective decoding method thereof.

Accordingly, the present invention has been designed to solve at least the above problems occurring in the prior art, and at least provide the following advantages.

One aspect of the present invention is to provide an encoding method that increases the decoding performance of control information.

Another aspect of the present invention is to provide an encoding method for increasing the decoding performance of signal information after L1.

Another aspect of the present invention is to provide a method and apparatus for transmitting and receiving control information in a broadcast/communication system.

In accordance with an aspect of the present invention, a method for transmitting signal information in a broadcast/communication system is provided. The method includes: generating signal information including a plurality of segments; determining, based on the number of bits of the signal information and the number of input information bits of the encoder, the number of encoded blocks into which the signal information is to be encoded; The number of blocks segments each segment of the signal information; the input information bits of each coded block are constructed to include the segmented portion of each segment of the signal information; the input information bits are encoded into each coded block Medium; and transmit each coded block.

According to another aspect of the present invention, a method for receiving signal information in a broadcast/communication system is provided. The method includes: receiving an encoded block of signal information; acquiring a number of bits of signal information or a number of encoded blocks of signal information; decoding the encoded block; extracting the encoded block included in the decoded block Segmented signal information bit; and the points that will be extracted The segment signal information bit restores the state before the segment.

According to another aspect of the present invention, an apparatus for transmitting signal information in a broadcast/communication system is provided. The device comprises: a layer 1 (L1) signal information generator for generating signal information including a plurality of segments; and a controller for using the number of bits of the signal information and the number of input information bits of the encoder Determining the number of encoded blocks of signal information to be encoded; an encoder for segmenting each segment of the signal information based on the number of encoded blocks, constructing an input information bit for each encoded block And including a segmented portion of each segment of the signal information, and encoding the input information bits into each of the encoded blocks; and a transmitter for transmitting each of the encoded blocks.

According to another aspect of the present invention, an apparatus for receiving signal information in a broadcast/communication system is provided. The apparatus includes: a receiver for receiving an encoded block of signal information; a decoder for decoding the encoded block; and a controller for acquiring a number of bits of signal information or signal information a number of coded blocks, and a segmented signal information bit included in the decoded coded block; and a reassembly translator for reassembling the segmented signal information bits before segmentation status.

The above and other aspects, features and advantages of the present invention will be apparent from the description of the appended claims.

Various embodiments of the present invention are described in detail below with reference to the accompanying drawings. Detailed descriptions of well-known functions and configurations are omitted in the following description and the accompanying drawings to avoid unnecessarily obscuring the subject matter of the present invention.

Although the embodiments of the present invention are described below using LDPC coding, the present invention is also applicable to other types of coding.

Figure 2 illustrates conventional segmented control information in a broadcast/communication system. Specifically, FIG. 2 illustrates L1 configurable information 208 and L1 dynamic information 209 that encode L1 post-signal information corresponding to the L1 signal information.

Referring to FIG. 2, since the L1 configurable information 208 contains information that does not change in each frame but may sometimes change, the L1 configurable information in the Kth frame can be compared with the (K+1) message. The L1 configurable information in the box is the same. When the L1 configurable information contained in the Kth frame is the same as the L1 configurable information contained in the (K+1) frame, after receiving the (K+1) frame, the receiver The L1 configurable information contained in the (K+1) frame can be known in advance via the L1 configurable information contained in the received Kth message frame. Therefore, the receiver can improve the performance of decoding the L1 dynamic information included in the (K+1) frame by using the previously known L1 configurable information.

More specifically, because the receiver receives the L1 configurable information contained in the Kth frame and transmits the same L1 configurable information in the (K+1) frame, when the receiver decodes the (K) When +1) frame, the receiver knows the L1 configurable information contained in the (K+1) frame.

In addition, even when the receiver fails to decode the Kth frame, the receiver can improve the L1 of the decoded (K+1) frame by using the L1 configurable information received in the Kth frame. Configuration information and the performance of L1 dynamic information. For example, when the L1 configurable information of the Kth frame is the same as the L1 configurable information of the (K+1) frame, the receiver can use the acquired pair. The Log Likelihood Ratio (LLR) value is used to decode the (K+1) frame even if the receiver fails to decode the L1 configurable information contained in the Kth frame.

When an LDPC code is used, the encoder encodes only the information bits, and the number of information bits is less than a predetermined number of input information bits (coding unit; the number of input information bits corresponding to the input size of the encoder). Therefore, in the LDPC encoding scheme, when the number of input information bits is greater than a predetermined number of information bits, the input information bits are segmented. In this paper, the information input to the encoder is called "input information bit", and the code word output after encoding by the encoder is called "coded block".

Referring to Figure 2, L1 configurable information 208 and L1 dynamic information 209 having variable length and corresponding to L1 post-signal information having size "a" are segmented into two coded blocks. When the number of bits of the signal information after L1 is greater than the predetermined number of encoder information bits, the L1 post signal information is segmented into two coded blocks. In this case, the first input information bit 210 is generated by extracting the a/2 portion from the post-L1 signal information, and the second input information bit 212 is generated by extracting the remaining a/2 from the post-L1 signal information. The first input information bit 210 includes an L1 configurable information ₁ (configurable ₁ ) 210 that is part of the L1 configurable information 208. That is, the first input information bit 210 contains only L1 configurable information 208. In addition, the second input information bit 212 includes L1 configurable information ₂ (Configurable ₂ ) 211, which is part of the L1 configurable information 208, and L1 dynamic information (L1 Dynamics) 209.

Assume that the L1 configurable information 208 included in the Kth frame is the same as the L1 configurable information 208 included in the (K+1) frame. Therefore, when the receiver receives the Kth frame and successfully decodes the L1 configurable information 208, there is an advantage that the receiver then does not have to decode the first input information bit 210 included in the (K+1)th frame. The first coded block. However, the second encoded block containing the second input information bit 212 contains L1 configurable information ₂ (Configurable ₂ ) 211 that is only part of the L1 configurable information 208. Thus, although the receiver is aware of the L1 configurable information 208, the number of bits of known information is not large enough to enable the receiver to significantly improve the performance of decoding the L1 dynamic information 209.

In accordance with an embodiment of the present invention, L1 configurable information 208 as illustrated in FIG. 2 is included in each of the first input information bit and the second input information bit.

In addition, in the LDPC encoding scheme, the decoding performance of the information located at the front portion of the encoder input information bit is generally better than the decoding performance of the information located at the rear portion of the encoder input information bit. Therefore, according to an embodiment of the present invention, when using LDPC, it is necessary to locate L1 dynamic information (that is, information that may be changed in each frame) at a portion of the input information bit to improve the receiver. Decoding performance.

3 illustrates a method for segmenting control information and generating an encoder input information bit in accordance with an embodiment of the present invention. Specifically, in FIG. 3, the segment value is equal to 2, which implies that the L1 signal information (specifically, the L1 post-signal information) to be encoded is divided into the first according to the coding unit corresponding to the input size of the encoder. An input information bit and a second input information bit are input, and the first input information bit and the second input information bit are input to the encoder. Therefore, when the segment value is equal to 2, the input will be encoded by the encoder. The information bit is divided into two coded blocks, and then two coded blocks are output from the encoder.

Referring to FIG. 3, according to the segmentation value 2, the L1 configurable information 301 is divided into two parts, that is, L1 configurable information ₁ (L1 configurable ₁ ) 303 and L1 configurable information ₂ (L1 can be Configuration ₂ ) 304. In addition, according to the segment value 2, the L1 dynamic information 302 is also divided into two parts, namely, L1 dynamic information ₁ (L1 dynamic ₁ ) 305 and L1 dynamic information ₂ (L1 dynamic ₂ ) 306.

In addition, the transmitter self-separating L1 configurable information ₁ (L1 configurable ₁ ) 303 and L1 dynamic information ₁ (L1 dynamic ₁ ) 305 construct the first encoder input information bit 310, and from L1 configurable information ₂ (L1 Configurable ₂ ) 304 and L1 Dynamic Information ₂ (L1 Dynamic ₂ ) 306 constructs a second encoder input information bit 320. The transmitter first inputs each of the first encoder input information bit 310 and the second encoder input information bit 320 to the LDPC encoder to generate two encoded blocks. In the first input information bit 310, the L1 dynamic information ₁ 305 is placed before the L1 configurable information ₁ 303. Similarly, in the second input information bit 320, the L1 dynamic information ₂ 306 is placed before the L1 configurable information ₂ 304.

Alternatively, the L1 dynamic information and the L1 configurable information can be interchanged with each other. For example, L1 configurable information ₁ 303 can be configured before L1 dynamic information ₁ 305, and L1 configurable information ₂ 304 can be configured before L1 dynamic information ₂ 306.

In addition, it is also possible to configure the L1 dynamic information 302 before the L1 configurable information 301 even when the encoder input information bits are not segmented. That is, even after L1, the length of the signal information is less than LDPC. The L1 dynamic information 302 can still be placed before the L1 configurable information 301 when the encoder information bits are predetermined by a predetermined number and therefore there is no need to segment the L1 post signal information.

4 illustrates a method for constructing an LDPC encoder input information bit without segmenting the L1 post-signal information, in accordance with an embodiment of the present invention.

Referring to FIG. 4, when the LDPC encoder input information bit is constructed by including the L1 configurable information 410 and the L1 dynamic information 411, the decoding performance of the bit located at the front portion of the input information bit is better than the input. The decoding performance of the bit at the rear portion of the information bit is as indicated by reference numeral 420, and the input information bit is constructed by arranging the L1 dynamic information 411 before the L1 configurable information 410.

FIG. 5 illustrates a method for constructing input information bits input to an encoder in accordance with an embodiment of the present invention. Specifically, FIG. 5 illustrates that a plurality of pieces of control information included in the L1 post-signal information are segmented according to the segment value 2.

Referring to FIG. 5, the L1 post signal 550 input to the encoder includes: L1 configurable information 500, L1 dynamic information of the current frame (or "current frame, dynamic" or "dynamic L1 post signal of current frame") 501, and L1 dynamic information (or "Next Frame, Dynamic" or "Dynamic L1 Post Signal of Next Frame") 502 of the next frame of the L1 dynamic information of the frame to be subsequently transmitted. Specifically, when the current frame is the Kth frame, the L1 dynamic information 502 of the next frame transmitted in the Kth frame contains the L1 dynamic information to be transmitted in the (K+1) frame. The same value. L1 dynamics of the next frame The information 502 is selective information, and the transmitter can inform the receiver via the L1 pre-signal whether there is L1 dynamic information of the next frame. For example, when the flag L1_REPETITION_FLG in the L1 pre-signal has a value of 1, this situation indicates that there is L1 dynamic information of the next frame. However, when L1_REPETITION_FLG has a value of 0, this situation indicates that there is no L1 dynamic information of the next frame.

Each of the L1 configurable information 500, the L1 dynamic information 501 of the current frame, and the L1 dynamic information 502 of the next frame is segmented into two parts. Specifically, as represented by reference numeral 510, the L1 configurable information 500 is divided into L1 configurable information ₁ (L1 configurable ₁ ) 504 and L1 configurable information ₂ (L1 configurable ₂ ) 505. As indicated by reference numeral 515, the L1 dynamic information 501 of the current frame is divided into L1 dynamic information _{1 of the} current frame (L1 dynamic _{1 of the} current frame) 506 and L1 dynamic information _{2 of the} current frame (current message) Box L1 Dynamic ₂ ) 507. As indicated by reference numeral 520, the L1 dynamic information 502 of the next frame is divided into L1 dynamic information _{1 of the} next frame (L1 dynamic _{1 of the} next frame) 508 and L1 dynamic information of the next frame. ₂ (L1 dynamic _{2 of the} next frame) 509.

During encoding, the L1 configurable information ₁ 504, the L1 dynamic information ₁ 506 of the current frame, and the L1 dynamic information ₁ 508 of the next frame are constructed as the first input information bit 530. In addition, the L1 configurable information ₂ 505, the L1 dynamic information ₂ 507 of the current frame, and the L1 dynamic information ₂ 509 of the next frame are constructed as the second input information bit 535.

The L1 configurable information ₁ 504 is disposed at the last portion of the first input information bit 530 after the L1 dynamic information ₁ 506 of the current frame and the L1 dynamic information ₁ 508 of the next frame.

Similarly, L1 configurable information ₂₅₀₅ located at the last portion of the second input information bits 535 after the current L1 L1 dynamic information of the frame information ₂₅₀₇ and the next information block ₂₅₀₉ of dynamic information.

Similar to in LDPC encoding, as described above, constructing the first input information bit 530 and the second input information bit 535 is better based on the decoding performance of the bit located at the front portion of the information bit. Therefore, the actual positioning visual decoding performance of the L1 configurable information 500 in the first input information bit 530 and the second input information bit 535, the L1 dynamic information 501 of the current frame, and the L1 dynamic information 502 of the next frame The change, for example, changes based on the type of encoding used.

Furthermore, as described above with reference to FIG. 4, even when segmentation is not required, it is considered that the decoding performance of the bit located at the front portion of the input information bit is better when the LDPC encoding scheme is used, and the current frame L1 The dynamic information can be located at the top of the input information bit, and the L1 configurable information can be located at the last part of the input information bit.

Therefore, regardless of whether or not to apply the segmentation, the L1 dynamic information and the positioning of the L1 configurable information can be determined by considering the coding performance of the input information bit of the LDPC encoder. That is, as described above, the L1 configurable information is configurable when the decoding performance of the bit located at the rear portion of the input information bit is better than the decoding performance of the bit located at the front portion of the input information bit. At the front part of the input information bit, and the L1 dynamic information can be configured at the rear part of the input information bit.

In addition, L1 configurable information and L1 dynamic information can be encoded/decoded independently of each other. Specifically, when the L1 dynamic information includes the L1 dynamic information of the current frame and the L1 dynamic information of the next frame, as described above, the optional dynamic information of the current frame and the L1 dynamic information of the next frame are included. Each of the segments is segmented, and the first input information bit corresponding to the unit input to the encoder is segmented L1 dynamic information ₁ constructed from the current frame and segmented L1 dynamic information of the next frame. ₁ . Further, a second input corresponding to the input information bits to an encoder unit is the construction information from the current frame through the through L1 dynamic information segment information of the next frame ₂ and the L1 dynamic information of the segment _2. In addition, regardless of whether segmentation is required, the L1 dynamic information of the current frame is disposed in the front part of the input information bit, and the L1 dynamic information of the next frame is disposed at the rear part of the input information bit.

Figure 6 illustrates the invention in accordance with the present invention The input of the embodiment to the segment of the input information bit of the encoder. In Figure 6, the segmentation value is N _{post_FEC_Block} .

Referring to FIG. 6, after L1, the signal information 650 (that is, the information bit input to the encoder) includes L1 configurable information 600, L1 dynamic information 601 of the current frame, L1 dynamic information 602 of the next frame, and extension. Information 603, CRC (Cyclic Redundancy Check) information 604 and L1 fill bit 605. The CRC information 604 includes the parity bit of the CRC code, and the receiver uses the same bit to determine whether the error occurs in the L1 configurable information 600, the L1 dynamic information 601 of the current frame, and the L1 dynamic information of the next frame. 602 and extension information 603. Although not illustrated in Figure 6, multiple CRCs can be used. In particular, the number of CRCs and their location can be varied, as will be apparent to those skilled in the art.

The length of the L1 configurable information 600 is K _{L1_conf} , the length of the L1 dynamic information 601 of the current frame is K _{L1_dyn, c} , the length of the L1 dynamic information 602 of the next frame is K _{L1_dyn, n} , the length of the extended information 603 Is K _{L1_ext} and the length of CRC 604 is N _crc . When K _{L1_dyn,n} (that is, the length of the L1 dynamic information 602 of the next frame) is equal to 0, the value of 0 indicates that the L1 dynamic information 602 of the next frame is not used. When K _{L1_ext} is equal to 0, this situation indicates that the extended information 603 is not used. Similarly, when N _crc is equal to 0, this situation indicates that the CRC code is not used.

_{Each of} K _{L1_conf} , K _{L1_dyn, c} and K _{L1_dyn,n} can be expressed as a function of the number of PLPs. It is possible to know K _{L1_conf} , K _{L1_dyn , c} and K _{L1_dyn,n} via other predetermined signals in other ways. For example, the parameters of the respective representation lengths may be transmitted via the L1 pre-information 105, such as _{L1_POST_CONF_SIZE} indicating K _{L1_conf} , L1_POST_DYN representing K _{L1_dyn, c} , CURRENT_SIZE, _{1_POST_DYN} representing N _{L1_dyn, n} , and NEXT_SIZE and indicating extended information 603 L1_POST_EXT_SIZE of length.

When the Bose Chaudhuri Hocquenghem (BCH) code is concatenated with the LDPC code and the BCH code serially connected to the LDPC code is used for the L1 signal information, and the length of the input bit of the BCH code is K _bch , the information corresponding to the L1 signal information is encoded. The N _{post_FEC_Block} of the number of _blocks can be calculated using the following equation (1). Basically, N _{post_FEC_Block} is the number of segments of the information into which the L1 signal information bits are segmented. When considering the concatenation of the BCH code and the LDPC code, the number of coded blocks can be calculated by using the length K _bch of the input bit of the BCH code. However, when only the LDPC code is used, the number of coded blocks can be calculated by using the length K _ldpc of the input bit of the LDPC code instead of K _bch .

In equation (1), K _{post_ex_pad} is the _{sum of the lengths} of the L1 configurable information 600, the L1 dynamic information 601 of the current frame, the L1 dynamic information 602 of the next frame, the extended information 603, and the CRC information 604. K _{post_ex_pad} =K _{L1_conf} +K _{L1_dyn,c} +K _{L1_dyn,n} +K _{L1_ext} +N _crc . That is, K _{post_ex_pad} is the number of bits of the L1 post signal that will exclude the padding field. In equation (1), Represents the smallest integer greater than x. For example, .

Based on N _{post_FEC_Block} corresponding to the number of encoded blocks, the K _pad corresponding to the length of the inserted zero bit can be calculated by using the following equation (2).

In equation (2), Represents the smallest integer greater than x. For example, . A K _pad corresponding to the length of the inserted zero bit can be omitted.

As described above with reference to FIG. 3 and FIG. 5, when L1 configurable information 600, L1 dynamic information 601 of the current frame, L1 dynamic information 602 of the next frame, extended information 603, CRC information 604, and L1 padding 605 When each of the segments is segmented according to N _{post_FEC_Block} , the length of each of the segments can be calculated using equations (3) through (6) below.

Specifically, the correction factor K _{L1_conf_PAD} of the L1 configurable information 600 of length K _{L1_conf} can be calculated by using equation (3). That is, when the length K _{L1_conf of the} L1 configurable information _does not correspond to a multiple of N _{post_FEC_Block for} the number of encoded blocks of the segment, K _{L1_conf_PAD} is a correction factor.

In equation (3), Represents the largest integer less than x. For example, . The value of K _{L1_conf_PAD} is such that the length of the L1 configurable information _i 600b in the i-th (i = 1, ..., (N _{post_FEC_Block} - 1)) encoder input information bit is And causing the length of the L1 configurable information 600c in the (N _{post_FEC_Block} ) encoder input information bit to be .

For example, when KL1_conf=299 and Npost_FEC_Block=2, .

The K _{L1_conf_PAD} having a value of 1 causes the length of the L1 configurable information _{1 in} the first encoder input information bit to be 149, and the length of the L1 configurable information _{2 in} the second encoder input information bit is 149. +1=150. These conditions are intended to prevent additional zero padding.

As illustrated in Figure 6, a length of _{K L1_dyn, c} is the length of the current correction factor L1 dynamic information 601 of the information block _{K L1_dyn,} c_PAD may be calculated by using Equation (4). When the length K _{L1_dyn,c} of the L1 dynamic information 601 of the current frame is not a multiple of N _{post_FEC_Block} corresponding to the number of encoded blocks for segmentation, K _{L1_dyn, c_PAD} is a correction factor.

In equation (4), Represents the largest integer less than x.

As illustrated in Figure 6, a length of _{K L1_dyn,} the length correction factor of the L1 dynamic information 602 of the next frame of information _n the _{K L1_dyn,} n_PAD may be calculated by using Equation (5). When the length K _{L1_dyn,n} of the L1 dynamic information in the next frame _does not correspond to a multiple of N _{post_FEC_Block for} the number of encoded blocks of the segment, K _{L1_dyn, n_PAD} is a correction factor.

In equation (5), Represents the largest integer less than x.

As described above, the L1 dynamic information 602 of the next frame is not always used. In this case, the natural K _{L1_dyn,n} should be equal to zero. When _each of the extended information 603 having the length K _{L1_ext} , the CRC 604 having the length N _crc , and the L1 padding 605 having the length K _pad is segmented according to N _{post_FEC_Block} as in Equations (3) to (5), The length K _{L1_ext_PAD} of the correction factor of the extended information 603 + CRC 604 + L1 padding 605 can be calculated using Equation (6) below.

In equation (6), when the sum of the lengths of the extended information 603, the CRC 604, and the L1 padding 605 does not correspond to a multiple of N _{post_FEC_Block for} the number of encoded blocks of the segment, K _{L1_ext_PAD} is a correction factor, and Represents the largest integer less than x. As described above, K _pad is not always used, and in this case, K _pad is equal to zero. In addition, N _crc represents a CRC bit.

A program for calculating K _sig (i) corresponding to the number of i-th encoder input information bits 670 using a plurality of values (which are calculated using equations (1) to (6)) is obtained by equation (7) Defined.

In equation (7), Represents the largest integer less than x. For example, .

The number of (N _{post_FEC_Block} ) encoder input information bits 680 can be calculated by using equation (8).

In equation (8), Represents the largest integer less than x.

Although the above performs segmentation in such a manner that there is a length difference between K _sig (i) (i=1,...,(N _{post_FEC_Block} -1)) and K _sig (N _{post_FEC_Block} ), it is possible to K _sig (i The segmentation is performed in such a manner that no difference in length occurs between (i = 1, ..., (N _{post_FEC_Block} - 1)) and K _sig (N _{post_FEC_Block} ). Moreover, as described above, the change in equations can be made based on the number of CRCs used and their positioning.

For example, when the CRC code is applied to each of the L1 configurable information 600, the dynamic information of the current frame 601, and the dynamic information 602 of the next frame, K _{L1_conf} , K _{L1_dyn , c ,} and K _{L1_dyn, n} may include the number of CRC bits of the L1 configurable information 600, the number of CRC bits of the dynamic information 601 of the current frame, and the number of CRC bits of the next frame 602, respectively.

In FIG. 6, reference numeral 690 denotes a first encoder input information bit segmented into segments (N _{post_FEC_Block} ) by using equations (1) through (8) to segment all encoder input information bits represented by reference numeral 650. The encoder inputs the information bits. Although the segmentation operation is typically performed by an encoder, when the encoder includes an interleaver, the interleaver can interleave (segment) all of the segmented encoder input information bits (i.e., L1 signal information).

More specifically, reference numeral 690 indicates that the first encoder input information bit 660 includes information bits (segmented L1 padding bits) 600a, 601a, 602a, 603a, 604a, and 605a, the information bit 600a 601a, 602a, 603a, 604a, and 605a are obtained by _segmenting the encoder input information bits 600, 601, 602, 603, 604, and 605 according to N _{post_FEC_Block} . Reference numeral 690 indicates that the i-th encoder input information bit 670 includes information bits 600b, 601b, 602b, 603b, 604b, and 605b (which are different from the encoder input information bit 650), the information bits 600b, 601b. 602b, 603b, 604b, and 605b are obtained by _segmenting the encoder input information bits 600, 601, 602, 603, 604, and 605 according to N _{post_FEC_Block} . Reference numeral 690 indicates that the (N _{post_FEC_Block} ) encoder input information bit 680 includes the last segments 600c, 601c, 602c, 603c, 604c, and 605c of the information bits, the segments 600c, 601c, 602c, 603c 604c and 605c are obtained by _segmenting the encoder input information bits 600, 601, 602, 603, 604, and 605 according to N _{post_FEC_Block} .

Accordingly, the receiver receiving the input information bit 690 decodes the encoded block obtained by encoding the encoder input information bit 660, the encoder input information bit 670, and the encoder input information bit 680. Then, the receiver recombines the following states before the segment: the segmented L1 dynamic information bits 601a, 601b, and 601c of the current frame, the segmented L1 dynamic information bit 602a of the next frame, 602b and 602c, segmented extended information by segmented L1 configurable information bits 600a, 600b, and 600c Bits 603a, 603b, and 603c are padded CRC bits 604a, 604b, and 604c, and padded bits 605a, 605b, and 605c are segmented L1. Thus, the receiver can recover the original L1 post signal information.

When the receiving device according to the embodiment of the present invention knows the length K _{L1_conf of the} L1 configurable information 600, the length K _{L1_dyn,c} of the L1 dynamic information 601 of the current frame, and the length of the L1 dynamic information 602 of the next frame K _{L1_dyn When n} , the receiving device can easily recover the L1 post-signal information. In this regard, a transmission device in accordance with an embodiment of the present invention can transmit _{values of} K _{L1_conf} , K _{L1_dyn,c} and K _{L1_dyn,n} . Since each value of K _{L1_conf} , K _{L1_dyn, c} and K _{L1_dyn,n} can be expressed as a function of the number of PLPs, if the transmission device transmits the number of PLPs, the receiving device can recover the L1 post-signal information. Therefore, when the transmitting device includes, for example, NUM_PLP (number of PLPs) information corresponding to the number of PLPs in the L1 pre-information 105 illustrated in FIG. 1, the receiving device can efficiently receive the post-L1 signal information.

Even if the segmentation is not performed as illustrated in FIG. 4, if the transmission device transmits the number of PLPs, the receiving device can use the number of PLPs to recover L1 even when the L1 dynamic information 411 is transmitted before the L1 configurable information 410. Post signal information. In addition, if the L1 dynamic information transmitted in the Kth frame is the same as the L1 dynamic information transmitted in the (K+1) frame, the information is restored after the receiving device resumes the L1 in the (K+1) frame. At any time, regardless of whether the receiving device successfully decodes the L1 dynamic information in the Kth frame, the receiving device can use the L1 dynamic information in the Kth frame.

7 and 8 illustrate information bits input to an encoder in accordance with an embodiment of the present invention. In Figure 7, the L1 dynamic information is located after the L1 configurable information.

Referring to FIG. 7, the length of the L1 configurable information 721 is K _{L1_conf} , the length of the L1 dynamic information 722 of the current frame is K _{L1_dyn,c} , and the length of the L1 dynamic information 723 of the next frame is K _{L1_dyn,n} , extension The length of field 724 is K _{L1_ext} and the length of CRC 725 is N _crc .

The length K _{L1_conf of the} L1 configurable information 721 can be obtained using the number of parameters L1_POST_CONF_SIZE or PLP. The parameters (the number of L1_POST_CONF_SIZE or PLP) may be transmitted separately or together in the L1 pre-signal. The length K _{L1_dyn,c} of the L1 dynamic information 722 of the current frame can be obtained using the number of parameters L1_POST_DYN, CURRENT_SIZE or PLP. The parameters may be transmitted separately or together in the L1 pre-signal. The length K _{L1_dyn,n} of the L1 dynamic information 723 of the next frame can be obtained using the number of parameters L1_POST_DYN, NEXT_SIZE or PLP. The parameters may be transmitted separately or together in the L1 pre-signal. The length K _{L1_ext of the} extension field 724 can be obtained using the parameter L1_POST_EXT_SIZE. The length N _{crc of the} CRC 725 can be fixed, for example, 32.

Referring to Figure 7, the L1 post signal 720 includes a variable number of bits that are transmitted via one or more LDPC blocks based on the length of the L1 post signal. An LDPC block has the same meaning as an encoded block.

The N _{post_FEC_Block} corresponding to the number of LDPC blocks of the L1 post signal 720 is determined using Equation (9).

In equation (9), N _{post_FEC_Block} is equal to 1 when K _{bch is} greater than or equal to K _{post_ex_pad} . However, when K _{bch is} smaller than K _{post_ex_pad} , N _{post_FEC_Block} is . The value of A is such that the K _{sig representing} the number of information bits in the encoded block after segmentation is less than or equal to the correction factor of K _bch and may vary depending on the number of types of segmented signals. For example, when each of the L1 configurable information 721, the current frame L1 dynamic information 722, the next frame L1 dynamic information 723, and the extended information 724 is segmented, four segments of the information are made. Each of the segments is segmented. Thus, the value of A can be three.

When the L1 dynamic information 723 of the next frame is not used in any frame, the value of A can be 2, but for the efficiency of the system, the value of A can be fixed to 3.

In equation (9), Represents the smallest integer equal to or greater than x, and the value of K _bch represents the number of BCH information bits.

Under the above situation, when the BCH code is concatenated with the LDPC code, the number of coded blocks is calculated using the length K _bch of the input bit of the BCH code. However, when only the LDPC code is used, the number of coded blocks can be calculated using the length K _ldpc of the input bit of the LDPC code instead of K _bch .

K _{post_ex_pad} is a value obtained by adding the length N _{crc of the} CRC 725 to the sum of the parameters L1_POST_CONF_SIZE, L1_POST_DYN, CURRENT_SIZE, L1_POST_DYN, NEXT_SIZE and L1_POST_EXT_SIZE, and the parameters L1_POST_CONF_SIZE, L1_POST_DYN, CURRENT_SIZE, L1_POST_DYN, NEXT_SIZE and L1_POST_EXT_SIZE respectively represent L1. The length of the configurable information 721, the length of the L1 dynamic information 722 of the current frame, the length of the L1 dynamic information 723 of the previous frame, and the length of the extended field 724. In addition, K _{post_ex_pad} indicates that the number of bits after the L1 signal will correspond to the L1_PADDING 726 that fills the field. The length N _{crc of the CRC} can be determined based on the maximum length of the signal after L1 (for example, 32). In this case, K _{L1_PADDING} corresponding to the length of the field named L1_PADDING 726 can be calculated using the following equation (10).

K _{L 1_ PADDING} = K _{L 1_ conf _ PAD} + K _{L 1_ dvn , c _ PAD} + K _{L 1_ dvn , n _ PAD} + K _{L 1_ ext _ PAD} (10)

In equation (10), K _{L1_conf_PAD} represents the length of the padding field of the L1 configurable information, K _{L1_dyn, c_PAD} represents the length of the padding field of the L1 dynamic information of the current frame, K _{L1_dyn, n_PAD} indicates the next message The length of the padding field of the L1 dynamic information information of the box, and K _{L1_ext_PAD} indicates the length of the padding field including the extended field 724 of the CRC 725. The lengths of each of L1_CONF_PAD 727, L1_DYN, C_PAD 728, L1_DYN, N_PAD 729, and L1_EXT_PAD 730 to fill the fields can be calculated using Equations (11) through (14) below.

In equations (11) to (14), K _{L1_conf} , K _{L1_dyn,c} , K _{L1_dyn,n} and K _{L1_ext} are values obtained using parameters L1_POST_CONF_SIZE, L1_POST_DYN, CURRENT_SIZE, L1_POST_DYN, NEXT_SIZE, and L1_POST_EXT_SIZE, respectively. These parameters represent the length of the L1 configurable information, the length of the L1 dynamic information of the current frame, the length of the L1 dynamic information of the next frame, and the length of the extended field. N _crc corresponds to the number of CRC bits (for example, 32). When L1_REPETITION_FLAG indicating whether to use the L1 dynamic information of the next frame is set to 0, the length K _{L1_dyn,n} of the L1 dynamic information of the next frame is 0.

The K _post corresponding to the final length of the signal after the entire L1 including the padding field can be defined using the following equation (15).

K _post =K _{post_ex_pad} +K _{L1_PADDING} ...(15)

In this case, K _sig corresponding to the number of information bits in each N _{post_FEC_Block} block can be defined using Equation (16) below.

As shown in Figure 7, for better performance, make L1 configurable information (configurable L1 post signal) 721, current frame L1 dynamic information (current frame dynamic L1 post signal) 722 and next The L1 dynamic information of the frame (the dynamic L1 post signal of the next frame) 723 is distributed as evenly as possible in all Forward Error Correction (FEC) blocks.

Specifically, the input bit of the first encoded block illustrated in FIG. 7 includes the first L1 configurable information (Configurable ₁ or Conf_1) 731, and the first L1 dynamic information of the current frame (current message) Dynamic ₁ or D, C_1) 732 of the frame, first L1 dynamic information of the next frame (Dynamic ₁ or D, N_1 of the next frame) 733 and the first extended field (Extension ₁ or E, C_1) 734 . The first L1 configurable information 731 includes bits in the L1 configurable information 710 One bit. The first L1 dynamic information 732 of the current frame includes one of the bits of the L1 dynamic information 722 of the current frame. The first L1 dynamic information 733 of the next frame contains the bits of the L1 dynamic information 723 of the next frame. One bit. The first extension field 734 includes bits in the extension field 724 and bits in the CRC 725. One bit.

In accordance with an embodiment of the present invention, the bit of the extended field 724 of the L1 post signal and the bit of the CRC 725 are all included in the first extended field 734 of the input bit of the first encoded block. From the first coded block to the ( N _{post _ FEC _ Block} -1) coded block, the above construction is performed by the same method.

The information bit in the (N _{post_FEC_Block} ) coded block contains the Nth configurable information (configurable _N or Conf_N) 739, the Nth dynamic information of the current frame (the dynamic _N or D of the current frame, C_N) 740, the Nth L1 dynamic information of the next frame (dynamic _N or D of the next frame, N_N) 741, the Nth extended field (extension _N or E, C_N) 742, and the padding field, such as L1_CONF_PAD 727, L1_DYN, C_PAD 728, L1_DYN, N_PAD 729, and L1_EXT_PAD 730. The Nth configurable information 739 includes bits in the L1 configurable information 710 One bit. The Nth L1 dynamic information 740 of the current frame includes the bits of the L1 dynamic information 722 of the current frame. One bit. The Nth L1 dynamic information 741 of the next frame contains the bits of the L1 dynamic information 723 of the next frame. One bit. The Nth extension field 742 includes the bit of the extended field 724 and the bit of the CRC 725. One bit.

In accordance with an embodiment of the present invention, the bit of the extended field 724 of the L1 post signal and the bit of the CRC 725 are all included in the first extended field 734 of the input bit of the first encoded block. K _{L1_ext_PAD} is the length of the padding field of the extended field 724 of the signal after L1 and the padding field of the bit of the CRC 725. 0 can be inserted into the fill field. In addition, you can change the position of the fill field.

For example, as illustrated in Figure 8, all padding fields can be located at the end of the encoded input.

According to an embodiment of the present invention, when the parameter L1_POST_EXT_SIZE is first set to a value including the length of the extended field and the length of the CRC instead of being set to only the length of the extended field and then transmitted, K _{L1_ext} can be regarded as The value obtained by adding the length of the extended field to N _crc . In this case, all N _crc can be deleted.

Figure 9 illustrates information bits input to an encoder in accordance with an embodiment of the present invention.

Referring to FIG. 9, the length of the L1 configurable information 921 is K _{L1_conf} , the length of the L1 dynamic information 922 of the current frame is K _{L1_dyn,c} , and the length of the L1 dynamic information 923 of the next frame is K _{L1_dyn,n} , The extension field 924 has a length of K _{L1_ext} and the length of the CRC 925 is N _crc .

The length K _{L1_conf of the} L1 configurable information 921 can be obtained using the parameter L1_POST_CONF_SIZE or using the number of PLPs. The length K _{L1_dyn,c} of the L1 dynamic information 922 of the current frame can be obtained using the parameters L1_POST_DYN, CURRENT_SIZE or the number of PLPs used. The length K _{L1_dyn,n} of the L1 dynamic information 923 of the next frame can be obtained using the parameters L1_POST_DYN, NEXT_SIZE or the number of PLPs used. The length K _{L1_ext of the} extension field 924 can be obtained using the parameter L1_POST_EXT_SIZE. The length N _{crc of the} CRC 925 can be, for example, 32. In this case, although the sum of the length of the L1 dynamic information 923 of the next frame and the length of the extended field 924 or the length of the CRC can be expressed as a parameter, in order to conveniently describe the present invention, it is assumed that the parameter exists separately. .

Referring to Figure 9, the L1 post signal 920 includes a variable number of bits, The bits are transmitted via one or more LDPC blocks according to the length of the L1 post signal. The LDPC block has the same meaning as the coded block illustrated in FIG.

N _{post_FEC_Block} corresponding to the number of LDPC blocks of the L1 post signal 920 is determined using the following equation (17).

In equation (17), N _{post_FEC_Block} is equal to 1 when K _{bch is} greater than or equal to K _{post_ex_pad} . However, when K _{bch is} smaller than K _{post_ex_pad} , N _{post_FEC_Block} is . The value of A is such that the K _sig of the number of information bits in the encoded block after segmentation is less than or equal to the correction factor of K _bch and may vary depending on the number of types of segmented signals.

For example, when the L1 configurable information 921, the L1 dynamic information 922 of the current frame, the L1 dynamic information 923 of the next frame, and the extended information 924 are segmented, three segments of the information are made. Each of the segments is segmented. Thus, the value of A can be 2.

In equation (17), Represents the smallest integer equal to or greater than x, and the value of K _bch represents the number of BCH information bits. When the BCH code is concatenated with the LDPC code, the number of coded blocks is calculated using the length K _bch of the input bit of the BCH code. However, when only the LDPC code is used, the number of coded blocks can be calculated using the length K _ldpc of the input bit of the LDPC code instead of K _bch .

K _{post_ex_pad} is a value obtained by adding the length N _{crc of the} CRC 925 to the sum of the parameters L1_POST_CONF_SIZE, L1_POST_DYN, CURRENT_SIZE, L1_POST_DYN, NEXT_SIZE and L1_POST_EXT_SIZE, and the parameters L1_POST_CONF_SIZE, L1_POST_DYN, CURRENT_SIZE, L1_POST_DYN, NEXT_SIZE and L1_POST_EXT_SIZE respectively represent L1 The length of the configuration information 921, the length of the L1 dynamic information 922 of the current frame, the length of the L1 dynamic information 923 of the previous frame, and the length of the extended field 924. In addition, K _{post_ex_pad} indicates that the number of bits after the L1 signal will correspond to the L1_PADDING 926 that fills the field. The length N _{crc of the CRC} can be determined based on the maximum length of the signal after L1.

K _{L1_PADDING} corresponding to the length of the field named L1_PADDING 926 can be calculated using the following equation (18).

K _{L1_PADDING} =K _{L1_conf_PAD} +K _{L1_dyn,c_PAD} +K _{L1_ext_PAD} ...(18)

In equation (18), K _{L1_conf_PAD} represents the length of the padding field of the L1 configurable information, K _{L1_dyn, c_PAD} represents the length of the padding field of the L1 dynamic information of the current frame, and K _{L1_ext_PAD} represents the next frame. The length of the padding field of the L1 dynamic information 923 and the extension field 924 of the CRC 925. The lengths of the L1_CONF_PAD 927, L1_DYN, C_PAD 928, and L1_EXT_PAD 930 to fill the fields can be calculated using equations (19), (20), and (21), respectively.

In equations (19) to (21), K _{L1_conf} , K _{L1_dyn,c} , K _{L1_dyn,n} and K _{L1_ext} are values that can be obtained using the parameters L1_POST_CONF_SIZE, L1_POST_DYN, CURRENT_SIZE, L1_POST_DYN, NEXT_SIZE, and L1_POST_EXT_SIZE, respectively. These parameters represent the length of the L1 configurable information 921, the length of the L1 dynamic information 922 of the current frame, the length of the L1 dynamic information 923 of the next frame, and the length of the extended field 924, respectively. N _crc corresponding to the number of CRC bits may be, for example, 32.

When L1_REPETITION_FLAG indicating whether to use the L1 dynamic information of the next frame is set to 0, the length K _{L1_dyn,n} of the L1 dynamic information of the next frame is equal to 0. In this case, the sum of the length of the dynamic information of the next frame and the length of the extended field can be expressed as a parameter. For example, (K _{L1_dyn, n} + K _{L1_ext} ) can be expressed as K _{L1_dyn, n, ext} , and K _{L1_dyn,n,ext} (L1_POST_DYN,N,EXT_SIZE) can be obtained using parameters each representing a respective length.

The K _post corresponding to the final length of the signal after the entire L1 including the padding field can be defined using Equation (22) below.

K _post =K _{post_ex_pad} +K _{L1_PADDING} ...(22)

K _sig corresponding to the number of information bits in each N _{post_FEC_Block} block can be defined using equation (23).

As shown in Figure 9, for better performance, make L1 configurable information (configurable L1 post signal) 921, current frame L1 dynamic information (current frame dynamic L1 post signal) 922, next The L1 dynamic information of the frame (the dynamic L1 post signal of the next frame) 923 and the extended field 924 are distributed as evenly as possible in all FEC blocks.

Specifically, the input bit of the first encoded block includes the first L1 configurable information (Configurable ₁ or Conf_1) 931, and the first L1 dynamic information of the current frame (Dynamic ₁ or D of the current frame) , C_1) 932 and the first extension field (Extension ₁ or E, C_1) 934. The first L1 configurable information 931 contains |K _{L1_conf} /N _{post_FEC_Block} | bits in the bits of the L1 configurable information 910. The first L1 dynamic information 932 of the current frame includes |K _{L1_dyn, c} /N _{post_FEC_Block} | bits in the bits of the L1 dynamic information 922 of the current frame. The first extension field 934 includes the bit of the L1 dynamic information 923 of the next frame, the bit of the extended field 924, and the bit of the CRC 925 | (K _{L1_dyn, n} + K _{L1_ext} + N _crc ) / N _{post_FEC_Block} | A bit. From the first encoded block to the (N _{post_FEC_Block} -1) encoded block, the above construction is performed by the same method.

The information bit in the (N _{post_FEC_Block} ) coded block contains the Nth configurable information (configurable _N or Conf_N) 939, the Nth dynamic information of the current frame (the dynamic _N or D of the current frame, C_N) 940, an Nth extension field (Extension _N or E, C_N) 942, and padding fields such as L1_CONF_PAD 927, L1_DYN, C_PAD 928, and L1_EXT_PAD 930. The Nth configurable information 939 contains |K _{L1_conf} /N _{pot_FEC_Block} |-K _{L1_conf_PAD} bits in the bits of the configurable information 910. The Nth L1 dynamic information 940 of the current frame includes (|K _{L1_dyn, c} /N _{post_FEC_Block} |-K _{L1_dyn, c_PAD} ) bits in the bits of the L1 dynamic information 922 of the current frame. The Nth extension field 942 includes the bit of the L1 dynamic information 923 of the next frame, the bit of the extended field 924, and the bit of the CRC 925 (|(K _{L1_dyn, n} + K _{L1_ext} + N _crc ) / N _{pot_FEC_Block} |-K _{L1_ext_PAD} ) bits. 0 can be inserted into the fill field. In addition, you can change the position of the fill field. For example, the fill field bit can be located at the end of the code input.

According to another embodiment of the present invention, the L1 of the current frame is considered to be moving. When the status information 722, the L1 dynamic information 723 of the next frame, the extended field 724, and the CRC 725 are one field, the segmentation is performed. In this case, the information obtained in the previous frame may not be used in the current frame L1 dynamic information 723 and the extended field 724 and CRC 725, and the L1 signal may or may not be included. The L1 dynamic information 723 and the extended field 724 of the next frame are included. Thus, the L1 dynamic information 723, the extended field 724, and the CRC 725 of the next frame can be considered to be a field to simplify the segmentation, and then the segmentation can be performed.

In this case, the correction factor A can be equal to 1 in equation (17). Based on the value of N _{post_FEC_Block} calculated using equation (17), equation (24) can be used to calculate the length K _{L1_PADDING of} field L1_PADDING 726.

K _{L1_PADDING} =K _{L1_conf_PAD} +K _{L1_ext_PAD} ...(24)

In equation (24), K _{L1_conf_PAD} represents the length of the padding field of the L1 configurable information, and K _{L1_ext_PAD} represents the _extension of the L1 dynamic information 722 containing the current frame, the L1 dynamic information 723 of the next frame, and the CRC 725. The length of the fill field of field 724. The lengths of L1_CONF_PAD and L1_EXT_PAD for filling the fields can be calculated using equations (25) and (26), respectively.

In equations (25) and (26), K _{L1_conf} , K _{L1_dyn,c} , K _{L1_dyn,n} and K _{L1_ext} are values calculated using parameters L1_POST_CONF_SIZE, L1_POST_DYN, CURRENT_SIZE, L1_POST_DYN, NEXT_SIZE, and L1_POST_EXT_SIZE, respectively. These parameters represent the length of the L1 configurable information 721, the length of the L1 dynamic information 722 of the current frame, the length of the L1 dynamic information 723 of the next frame, and the length of the extended field 724, respectively. N _crc corresponding to the number of CRC bits may be, for example, 32.

When L1_REPETITION_FLAG indicating whether to use the L1 dynamic information of the next frame is set to 0, the length K _{L1_dyn,n} of the L1 dynamic information of the next frame is equal to 0. In this case, the sum of the length of the dynamic information of the current frame, the length of the dynamic information of the next frame, and the length of the extended field can be expressed as a parameter.

According to another embodiment of the invention, the L1 post signal does not include an extended field 724. In this case, the value of K _{L1_ext} becomes 0, and only the segmented bits of the CRC field 725 are included in the extended fields 734, 738, and 742 of the segmented information bits input to the encoded block. in. In this case, the number of segmented bits of the CRC field can be extremely small, making the following operations inefficient: first, the extended field 724 and the CRC field 725 are segmented, and then extended from the segmentation. Fields 724 and segmented CRC field 725 construct extension fields 734, 738, and 742. Therefore, in this situation, it may be more efficient to segment the CRC field 725 with the L1 dynamic information 723 of the next frame.

Specifically, instead of having the extended field 724 and the CRC field 725 segmented simultaneously (because the value of the extended field is equal to 0), the L1 dynamic information 723 of the next frame is simultaneously segmented with the CRC field 725, and then The L1 dynamic information 723 and the segmented CRC field 725 of the next frame form the first L1 dynamic information 733 of the next frame, the second L1 dynamic information 737 of the next frame, and the next message. The (N _{post_FEC_Block} ) L1 dynamic information 741 of the box.

According to another embodiment of the present invention, the extended field and the L1 dynamic information 723 of the next frame do not exist. In this case, as described in the above examples, the number of segmented bits of the CRC field can be extremely small, such that the segments can be inefficient. Therefore, in this case, the CRC field 725 is segmented with the L1 dynamic information 722 of the current frame, and then constructed from the segmented CRC field 725 and the segmented current frame L1 dynamic information 722. The first L1 dynamic information 731 of the current frame, the second L1 dynamic information 735 of the current frame, and the (N _{post_FEC_Block} ) dynamic information 739 of the current frame.

10 is a flow chart illustrating a method for encoding control information and transmitting control information by a transmission device in accordance with an embodiment of the present invention.

Referring to FIG. 10, in step 1000, the transmitting device determines the L1 signal information and generates L1 pre-information and L1 post-signal information. However, since the present invention is related to encoding L1 post-signal information, the following description will not describe the encoding of the pre-L1 information.

In step 1002, the transmitting device determines the number of bits of the L1 post-signal information that will be excluded from the padding field. In step 1004, the transmitting device determines the number of encoded blocks for transmitting the L1 post-signal bits based on the number of bits and the coding unit of the L1 post-signal information that excludes the padding field. In this paper, the coding unit is the size of the encoder to perform encoding at one time, and is also referred to herein as the "number of encoder input information bits". When the BCH code is concatenated with the LDPC code, the coding unit is the number of information bits that are permitted to be input into the BCH encoder, and is therefore also referred to as a BCH information bit. In addition, the number of bits of the L1 post-signal information that is excluded from the fill field is equal to the number of bits of the L1 configurable information, the number of bits of the L1 dynamic information of the current frame, and the L1 dynamics of the next frame. The sum of the number of bits of information and the number of bits in the CRC and extension fields.

In step 1006, the transmitting device segments the post-L1 signal information based on the determined number of encoded blocks. The segmentation scheme can use the equations described above.

More specifically, in step 1006, first, a plurality of segments corresponding to the information (bits of L1 configurable information, bits of L1 dynamic information of the current frame, and bits of L1 dynamic information of the next frame) are first calculated. The number of padding elements of the correction factor for each of the elements, and the CRC and the extension field. The number of all padding bits of the L1 post signal is obtained by adding the first to fourth calculated numbers of the padding bits of the plurality of segments of the information.

Thereafter, after calculating the number of padding bits of the signal after L1 and the number of bits of the signal information after the L1 is excluded from the padding field, the L1 is calculated. The number of bits of the signal. The number of input bits per coded block can be obtained by dividing the calculated number of bits of the L1 post signal by the number of coded blocks. In other words, encoding is performed by inputting as many L1 post-signal bits as the number of input bits to the encoder.

Then, each of the plurality of segments above the information is made according to the determined number of the coded blocks (bits of the L1 configurable information, bits of the L1 dynamic information of the current frame, and the next frame) The bits of the L1 dynamic information, and the bits of the CRC and the extended field are segmented, and the input bits each having a code block corresponding to the length of the obtained number of input bits are constructed. In each of the plurality of segments above the information, the number of groups of coded input bits of the code block is equal to the determined number of coded blocks.

In step 1008, the transmitting device causes the L1 post-signal information segmented in step 1006 to be included in each of the first encoder input information bit to the (N _{post_FEC_Block} ) encoder input information bit. In step 1010, the transmitter encodes the first encoder input information bit to the (N _{post_FEC_Block} ) encoder input information bit, and then transmits the first encoded block to the (N _{post_FEC_Block} ) coded block to receiver.

In step 1012, after the transmitting device transmits the number of bits of the post-L1 signal information, the number of encoded blocks, or the number of PLPs to the receiving device, the transmitting device moves to the next frame in step 1014, and The next frame repeats steps 1000 through 1012.

In FIG. 10, although step 1012 has been described as being performed after performing step 1010, step 1012 may be performed prior to step 1010. Furthermore, although the transmission device has been described as having L1 post-signal information in step 1012 The number of bits, the number of coded blocks, or the number of PLPs is transmitted to the receiving device, but the transmitting device can transmit all of the information, or the transmitting device can transmit only some of the information (eg, the number of PLPs).

For example, in a broadcast/communication system according to an embodiment of the present invention, when the transmission device transmits the number of bits of the signal information after L1 and the information about the signal code (LDPC codeword length and code rate), the transmission is not transmitted. When encoding the number of blocks, the receiving device can estimate the number of coded blocks by using this information.

11 is a flow chart illustrating a method for receiving control information by a receiving device in accordance with an embodiment of the present invention.

Referring to FIG. 11, in step 1100, the receiving device receives the L1 signal information of the current frame. In step 1102, the receiving device acquires at least one of the following ones transmitted in the current frame: the number of bits of the post-L1 signal information, the number of encoded blocks, and the number of PLPs. Herein, the receiving device may receive the number of bits of the L1 post-signal information or the number of encoded blocks from the transmitting device, or may use previously determined information. This option can be changed depending on the user of the system. Moreover, although the pre-L1 information has been received in step 1100, the present invention is directed to post-L1 signal information, and the L1 pre-information is handled by a scheme implemented by the broadcast/communication system to which the present invention is applied. Therefore, a more detailed description of the information before L1 will be omitted.

In step 1104, the receiving device decodes the received encoded block. In step 1106, the receiving device extracts the segmented L1 post-signal information bits included in each of the decoded encoded blocks, and in steps In 1108 , the receiving device recomposes the L1 post-signal information bit extracted in step 1106 to return to the state prior to the segmentation.

In step 1110, the receiving device receives the data using the L1 post-signal information bit recombined in step 1108 and the L1 signal information different from the L1 post-signal information received in step 1100.

In step 1112, the receiving device moves to the next frame and repeats the operations in steps 1100 through 1110 for the next frame.

FIG. 12 is a block diagram illustrating a transmission device 1200 in accordance with an embodiment of the present invention.

Referring to Figure 12, the L1 signal information generator 1202 generates L1 signal information for the current frame. Specifically, the L1 signal information generator 1202 generates the L1 pre-information and the L1 post-signal information, and outputs the generated L1 pre-information and the generated L1 post-signal information to the encoder 1204. However, since the present invention is encoded with respect to post-L1 signal information, and the L1 pre-information is encoded by the broadcast/communication system to which the present invention is applied, the pre-L1 information will not be described in more detail herein.

The controller 1206 determines the number of bits of the L1 post-signal information that is excluded from the padding field generated by the L1 signal information generator 1202. The controller 1206 determines the number of coded blocks used to transmit the L1 post-signal bits based on the determined number and coding unit of the bit information of the post-L1 signal information that excludes the padding field. Further, the controller 1206 can determine the number of PLPs.

When the controller 1206 determines the number of encoded blocks, the controller 1206 segments the post-L1 signal information based on the determined number of encoded blocks. In addition, when the encoder 1204 includes an interleaver, the controller 1206 controls the handover. The wrong device is used to segment the signal information after L1. Otherwise, the controller 1206 can control the L1 signal information generator 1202 to segment the post-L1 signal information. The segmentation scheme can use the above equations.

More specifically, the controller 1206 first calculates a plurality of segments corresponding to the information (bits of the L1 configurable information, the bits of the L1 dynamic information of the current frame, and the bits of the L1 dynamic information of the next frame, And the number of padding bits of the correction factor for each of the CRC and the extension field. The controller then obtains the number of all padding bits of the post-L1 signal by adding the first to fourth calculated numbers of the padding bits of the plurality of segments of the information. The controller calculates the number of all bits of the L1 post signal using the number of padding bits obtained after the L1 signal and the number of bits of the L1 post signal information excluding the determined padding field. The number of input bits required per coded block can be obtained by dividing the calculated number of bits of the L1 post signal by the determined number of coded blocks. In other words, encoding is performed by inputting as many L1 post-signal bits as the number of input bits to the encoder.

The controller performs a control operation to cause a plurality of segments of the information according to the determined number of the coded blocks (bits of the L1 configurable information, bits of the L1 dynamic information of the current frame, and L1 dynamics of the next frame) The bits of the information, and the bits of the CRC and the extended field are segmented, and the input bits each having a code block corresponding to the length of the obtained number of input bits are constructed. The number of groups of input blocks constructed by the code block is equal to the determined number of coded blocks.

The controller 1206 controls the encoder 1204 or the L1 signal information generator 1202 to include the segmented L1 post signal information in each of the first encoder input information bits to the (N _{post_FEC_Block} ) encoder input information bits. in. The encoder 1204 first encodes the first encoder input information bit to the (N _{post_FEC_Block} ) encoder input information bit, and then outputs the first encoded block to the (N _{post_FEC_Block} ) encoded block to the transmitter 1208. . The transmitter 1208 transmits the encoded block to the receiving device frame by frame according to the control of the controller 1206. Additionally, the transmitter 1208 can transmit the number of PLPs that have been determined by the controller 1206 to the receiving device.

FIG. 13 is a block diagram illustrating a receiving device 1300 in accordance with an embodiment of the present invention.

Referring to FIG. 13, the receiver 1302 receives the L1 signal information of the current frame, and outputs the received L1 signal information of the current frame to the decoder 1304. In addition, the receiver 1302 receives at least one of the number of bits of the post-L1 signal information, the number of encoded blocks, and the number of PLPs transmitted in the current frame, and outputs the received data to the controller 1306. . Herein, the controller 1306 can receive the number of bits of L1 post-signal information, the number of encoded blocks, or the number of PLPs from the transmitting device, or can use previously determined information. This option can be changed depending on the user of the system. In addition, although the receiver 1302 also receives the pre-L1 information, since the present invention is directed to the post-L1 signal information, and the L1 pre-information is processed by the scheme implemented by the broadcast/communication system to which the present invention is applied, the pre-L1 information will be omitted. More detailed description.

The decoder 1304 decodes the received encoded block.

According to an embodiment of the present invention, the controller 1306 performs extraction for extracting a package Control operations of the segmented L1 post-signal information bits contained in each of the decoded encoded blocks. The retranslator 1308 reassembles the extracted L1 post-signal information bits in accordance with the control of the controller 1306 to return to the state prior to the segmentation. That is, the controller 1306 calculates the segmentation value by using one of the number of bits of the post-L1 signal information, the number of encoded blocks, and the number of PLPs, and notifies the recombination translator 108 of the calculated value. Segmentation value. Thus, the controller 1306 enables recovery of the original L1 post-signal information by performing the program executed by the transmitting device in reverse.

The controller 1306 controls the receiver 1302 to receive the data using the recombined L1 post-signal information bit and the L1 signal information different from the L1 post-signal information.

As described above, although the L1 configurable information and the L1 dynamic information are referred to as "L1 post signal information", this is a term used in the application of the present invention to DVB-T2 (Digital Video Terrestrial Broadcasting 2). Thus, when the present invention is applied to DVB-C2 (Cable Digital Video Broadcasting 2), L1 configurable information and L1 dynamic information may also be referred to as "Part II Signal Information".

In addition, the above embodiments of the present invention can also be implemented as a code that can be recorded by a computer in a non-transitory computer recordable recording medium.

For example, the computer recordable recording medium can be an optional data storage device that can store data that can be read by a computer system.

Examples of non-transitory computer recordable recording media include read only memory (ROM), random access memory (RAM), compact disc (CD), magnetic tape, flexible magnetic disk, and optical data storage devices. However, the invention is not limited to this Etc.

According to the above embodiment of the present invention, the transmitter encodes control information to effectively change the control information so that the receiver can improve the decoding performance.

Although the present invention has been shown and described with respect to the embodiments of the present invention, it will be understood by those skilled in the art that various changes in form and detail may be made in the present invention without departing from the spirit and scope of the invention. Therefore, the spirit and scope of the invention are not limited to the described embodiments of the invention, but are defined by the scope of the appended claims and their equivalents.

101‧‧‧ frame

102‧‧‧ preamble

103‧‧‧layer 1 (L1) signal

104‧‧‧Information

105‧‧‧L1 pre-information

106‧‧‧L1 configurable information

107‧‧‧L1 Dynamic Information

108‧‧‧ Physical Layer Pipeline (PLP)

109‧‧‧ Physical Layer Pipeline (PLP)

110‧‧‧Physical Layer Pipeline (PLP)

120‧‧‧L1 post signal information

208‧‧‧L1 configurable information

209‧‧‧L1 Dynamic Information

210‧‧‧First input information bit

211‧‧‧L1 configurable information ₂

212‧‧‧Second input information bit

301‧‧‧L1 configurable information

302‧‧‧L1 Dynamic Information

303‧‧‧L1 configurable information ₁

304‧‧‧L1 configurable information ₂

305‧‧‧L1 Dynamic Information ₁

306‧‧‧L1 Dynamic Information ₂

310‧‧‧The first encoder input information bit

320‧‧‧Second encoder input information bit

410‧‧‧L1 configurable information

411‧‧‧L1 Dynamic Information

500‧‧‧L1 configurable information

501‧‧‧L1 dynamic information of the current frame

502‧‧‧L1 dynamic information in the next frame

504‧‧‧L1 configurable information ₁

505‧‧‧L1 configurable information ₂

506‧‧‧L1 dynamic information of the current frame ₁

507‧‧‧L1 dynamic information of the current frame ₂

508‧‧‧L1 Newsletter ₁

509‧‧‧L1 dynamic information of the next frame ₂

530‧‧‧First input information bit

535‧‧‧Second input information bit

550‧‧‧L1 post signal

600‧‧‧L1 configurable information

600a‧‧‧Information Bits

600b‧‧‧Information Bits

600c‧‧‧ information bits

601‧‧‧L1 dynamic information of the current frame

601a‧‧‧Information Bits

601b‧‧‧Information Bits

601c‧‧‧Information Bits

602‧‧‧L1 dynamic information in the next frame

602a‧‧‧Information Bits

602b‧‧‧Information Bits

602c‧‧‧Information Bits

603‧‧‧Extended information

603a‧‧‧Information Bits

603b‧‧‧Information Bits

603c‧‧‧Information Bits

604‧‧‧CRC (Cyclic Redundancy Check) Information

604a‧‧‧Information Bits

604b‧‧‧Information Bits

604c‧‧‧Information Bits

605‧‧‧L1 fills the bit

605a‧‧‧Information Bits

605b‧‧‧Information Bits

605c‧‧‧Information Bits

650‧‧‧L1 post signal information

660‧‧‧First encoder input information bit

670‧‧‧i-i encoder input information bit

680‧‧‧Encoder input information bit

690‧‧‧Enter information bits

710‧‧‧L1 configurable information

720‧‧‧L1 post signal

721‧‧‧L1 configurable information

722‧‧‧L1 dynamic information of the current frame

723‧‧‧L1 dynamic information in the next frame

724‧‧‧Extended field

725‧‧‧CRC

726‧‧‧Filling the field

727‧‧‧L1_CONF_PAD/Filling the field

728‧‧‧L1_DYN, C_PAD/filling the field

729‧‧‧L1_DYN, N_PAD/filling the field

730‧‧‧L1_EXT_PAD/Filling the field

731‧‧‧First L1 configurable information

732‧‧‧The first L1 dynamic information of the current frame

733‧‧‧L1 dynamic information in the next frame

734‧‧‧First extended field

735‧‧‧The second L1 dynamic information of the current frame

737‧‧‧The second L1 dynamic information of the next frame

738‧‧‧Extended field

739‧‧‧Nth configurable information

740‧‧‧Nth dynamic information of the current frame

741‧‧‧Nth dynamic information of the next frame

742‧‧‧Nth extension field

910‧‧‧L1 configurable information

920‧‧‧L1 post signal

921‧‧‧L1 configurable information

922‧‧‧L1 dynamic information of the current frame

923‧‧‧L1 dynamic information in the next frame

924‧‧‧Extension field

925‧‧‧CRC

926‧‧‧L1_PADDING/Filling the field

927‧‧‧L1_CONF_PAD/Filling the field

928‧‧‧L1_DYN, C_PAD/filling the field

930‧‧‧L1_EXT_PAD/Filling the field

931‧‧‧First L1 configurable information

932‧‧‧ The first L1 dynamic information of the current frame

934‧‧‧First expansion field

939‧‧‧Nth configurable information

940‧‧‧Nth dynamic information of the current frame

942‧‧‧Nth extension field

1000~1014‧‧ steps of the method for transmitting control information by the transmission device of the embodiment of the present invention

1100 to 1112‧‧ steps of a method of receiving control information by a receiving device of an embodiment of the present invention

1200‧‧‧Transmission device

1202‧‧‧L1 signal information generator

1204‧‧‧Encoder

1206‧‧‧ Controller

1208‧‧‧Transmitter

1300‧‧‧ receiving device

1302‧‧‧ Receiver

1304‧‧‧Decoder

1306‧‧‧ Controller

1308‧‧‧Reorganized translator

Figure 1 illustrates a frame for use in a conventional broadcast/communication system.

Figure 2 illustrates conventional segmentation control information in a broadcast/communication system.

3 illustrates a method for segmenting control information and generating an encoder input information bit in accordance with an embodiment of the present invention.

4 illustrates a method for generating an encoder input information bit without segmenting control information in accordance with an embodiment of the present invention.

FIG. 5 illustrates a method for constructing input information bits input to an encoder in accordance with an embodiment of the present invention.

Figure 6 illustrates the invention in accordance with the present invention The input of the embodiment to the information bits of the encoder.

7 and 8 illustrate information bits input to an encoder in accordance with an embodiment of the present invention.

Figure 9 illustrates information bits input to an encoder in accordance with an embodiment of the present invention.

FIG. 10 is a diagram illustrating coding control resources according to an embodiment of the present invention. A flow chart of a method of transmitting control information by a transmission device.

11 is a flow chart illustrating a method for receiving control information by a receiving device in accordance with an embodiment of the present invention.

Figure 12 is a block diagram illustrating a transmission device in accordance with an embodiment of the present invention. And Figure 13 is a block diagram illustrating a receiving device in accordance with an embodiment of the present invention.

1000~1014‧‧ steps of the method for transmitting control information by the transmission device of the embodiment of the present invention

Claims (18)

A method for transmitting signal information by a transmitter in a broadcast/communication system, the method comprising: generating the signal information including a plurality of segments; based on a number of bits of the signal information and an encoder input information bit The number of elements to determine the number of encoded blocks into which the signal information is to be encoded; each segment of the signal information is segmented based on the number of the encoded blocks; constructing each coded block Inputting an information bit to include a segmented portion of each segment of the signal information; encoding the input information bit into each encoded block; and transmitting each encoded block. A method for receiving signal information by a receiver in a broadcast/communication system, the method comprising: receiving an encoded block of the signal information, wherein a number of bits based on the signal information and an encoder input information Number of the encoded blocks, wherein each segment of the signal information is segmented based on the number of the encoded blocks; the number or location of the bits of the signal information is obtained Said number of said encoded blocks of signal information; decoding said encoded block; extracting segmented signal information bits included in said decoded encoded block; and extracting said extracting The segmented signal information bit is restored to the state before the segment. The method of claim 1, or the method of claim 2, wherein the signal information comprises layer 1 (L1) configurable information and L1 dynamic information. The method of claim 3, wherein the L1 dynamic information includes L1 dynamic information of the current frame and L1 dynamic information of the next frame. The method of claim 3, wherein the signal information further comprises at least one of an extended field, a cyclic redundancy check (CRC) field, and a padding field. The method of claim 1, or the method of claim 2, wherein the number of the coded blocks is defined by: Where N _{post_FEC_Block} represents the number of coded blocks, K _{post_ex_pad} represents the number of signal bits excluding the padding field, K _bch corresponds to the coding unit, and represents the bit coded by the encoder in one time unit The number, K _{bch ,} represents the number of BCH information bits that are allowed to be input to the BCH encoder when the Bose Chaudhuri Hocquenghem (BCH) code is concatenated with the Low Density Parity Check (LDPC) code, and A represents the correction factor. In the method of claim 5, the length of the padding field is defined by: K _{L1_PADDING} = K _{L1_conf_PAD} + K _{L1_dyn, c_PAD} + K _{L1_dyn, n_PAD} + K _{L1_ext_PAD} , where K _{L1_PADDING} indicates Fill the length of the field, K _{L1_conf} _ _PAD indicates the length of the padding field of the L1 configurable information, K _{L1_dyn, c_PAD} indicates the length of the padding field of the L1 dynamic information of the current frame, K _{L1_dyn, n_PAD} The length of the padding field of the L1 dynamic information of the next frame, and K _{L1_ext_PAD} indicates the length of the padding field of the extended field including the CRC. For example, the method described in claim 7 wherein K _{L1_conf_PAD is determined} by the following formula: Where K _{L1_dyn, c_PAD} is defined by: Where K _{L1_dyn, n_PAD} is defined by: And wherein K _{L1_ext_PAD} is defined by the following formula: Where K _{L1_conf} represents the length of the L1 configurable information, K _{L1_dyn,c} represents the length of the L1 dynamic information of the current frame, and K _{L1_dyn,n} represents the L1 dynamic information of the next frame. The length, K _{L1_ext} represents the length of the extended field, N _crc represents the length of the CRC field, and N _{post_FEC_Block} represents the number of encoded blocks. The method of claim 1, or the method of claim 2, wherein the length of the input information bit of each coded block is defined by: Where K _sig represents the length of the input information bit of each coded block, N _{post_FEC_Block} represents the number of coded blocks, and K _post is defined by: K _post =K _{post_ex_pad} + K _{L1_PADDING} , where K _{post_ex_pad} represents the number of signal bits that will exclude the padding field, and K _{L1_PADDING} represents the length of the padding field. An apparatus for transmitting signal information in a broadcast/communication system, the apparatus comprising: a layer 1 (L1) signal information generator for generating the signal information including a plurality of segments; a controller for determining based on a number of bits of the signal information and a number of encoder input information bits The signal information is to be encoded into a number of encoded blocks; an encoder for segmenting each segment of the signal information and constructing each coded region based on the number of the encoded blocks Input information bits of the block to include a segmented portion of each segment of the signal information, and encoding the input information bits into each encoded block; and a transmitter for transmitting each encoded block Block. An apparatus for receiving signal information in a broadcast/communication system, the apparatus comprising: a receiver for receiving an encoded block of the signal information, wherein a number of bits and an encoder based on the signal information Determining the number of encoded blocks by the number of input information, wherein each segment of the signal information is segmented based on the number of the encoded blocks; a decoder for decoding the encoded a controller that acquires the number of bits of the signal information or the number of the encoded blocks of the signal information, and extracts the decoded block included in the decoded block a segmented signal information bit; and a recombination translator for recombining the segmented signal information bits before the segment is translated into segments. Such as the device described in claim 10 or The device of claim 11, wherein the signal information comprises layer 1 (L1) configurable information and L1 dynamic information. The device of claim 12, wherein the L1 dynamic information comprises L1 dynamic information of a current frame and L1 dynamic information of a next frame. The apparatus of claim 12, wherein the signal information further comprises at least one of an extended field, a cyclic redundancy check (CRC) field, and a padding field. The device of claim 10, or the device of claim 11, wherein the number of the coded blocks is defined by: Where N _{post_FEC_Block} represents the number of encoded blocks, K _{post_ex_pad} represents the number of signal bits excluding the padding field, K _bch corresponds to the coding unit and represents the bit of the encoder encoded in a time unit The number, K _{bch ,} represents the number of BCH information bits that are allowed to be input to the BCH encoder when the Bose Chaudhuri Hocquenghem (BCH) code is concatenated with the low density parity check low density parity check (LDPC) code, and A represents the correction. Factor. The device of claim 14, wherein the length of the padding field is defined by: K _{L1_PADDING} = K _{L1_conf_PAD} + K _{L1_dyn, c_PAD} + K _{L1_dyn, n_PAD} + K _{L1_ext_PAD} , wherein K _{L1_PADDING} represents The length of the padding field, K _{L1_conf_PAD} indicates the length of the padding field of the L1 configurable information, K _{L1_dyn, c_PAD} indicates the length of the padding field of the L1 dynamic information of the current frame, K _{L1_dyn, n_PAD} indicates The L1 dynamic information of the frame fills the length of the field, and K _{L1_ext_PAD} represents the length of the padding field of the extended field containing the CRC. The device of claim 16, wherein K _{L1_conf_PAD} is defined by: Where K _{L1_dyn, c_PAD} is defined by: Where K _{L1_dyn, n_PAD} is defined by: And wherein K _{L1_ext_PAD} is defined by the following formula: Where K _{L1_conf} represents the length of the L1 configurable information, K _{L1_dyn,c} represents the length of the L1 dynamic information of the current frame, and K _{L1_dyn,n} represents the L1 dynamic information of the next frame. The length, K _{L1_ext} represents the length of the extended field, N _crc represents the length of the CRC field, and N _{post_FEC_Block} represents the number of encoded blocks. The device of claim 10, or the device of claim 11, wherein the length of the input information bit of each coded block is defined by: Where K _sig represents the length of the input information bit of each coded block, N _{post_FEC_Block} represents the number of coded blocks, and K _post is defined by: K _post =K _{post_ex_pad} +K _{L1_PADDING} , where K _{post_ex_pad} represents the number of signal bits that will exclude the padding field, and K _{L1_PADDING} represents the length of the padding field.