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7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.4 Compensating Delay for Transport Streams | The interleaving parameters PI and NTI (see clause 6.5), and the frame interval IJUMP (see clause 8.2) may be different for the Data PLPs in a group and the corresponding Common PLP. In order to allow the Transport Stream recombining mechanism described in annex D without requiring additional memory in the receiver, th... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.5 Null-Packet Deletion (optional, for TS only, NM and HEM) | Transport Stream rules require that bit rates at the output of the transmitter's multiplexer and at the input of the receiver's de-multiplexer are constant in time and the end-to-end delay is also constant. For some Transport-Stream input signals, a large percentage of null packets may be present in order to accommodat... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.6 CRC-8 encoding (for GFPS and TS, NM only) | CRC-8 is applied for error detection at UP level (Normal Mode and packetized streams only). When applicable (see clause 5.1.8), the UPL-8 bits of the UP (after sync-byte removal, when applicable) shall be processed by the systematic 8-bit CRC-8 encoder defined in annex F. The computed CRC-8 shall be appended after the ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.7 Baseband Header (BBHEADER) insertion | A fixed length BBHEADER of 10 bytes shall be inserted in front of the baseband DATA FIELD in order to describe the format of the DATA FIELD. The BBHEADER shall take one of two forms as shown in figure 4 a) for Normal Mode (NM) and in figure 4 b) for High Efficiency Mode (HEM). The current mode (NM or HEM) may be detect... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.8 Mode Adaptation sub-system output stream formats | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.8.0 Introduction | This clause describes the Mode Adaptation processing and fragmentation for the various modes and input stream formats, as well as illustrating the output stream format. |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.8.1 Normal Mode, GFPS and TS | See clause 5.1.7 for BBHEADER signalling. For Transport Stream, O-UPL = 188 x 8 bits, and the first byte shall be a sync byte (0x47). UPL (the transmitted User Packet Length) shall initially be set equal to O-UPL. The Mode Adaptation unit shall perform the following sequence of operations (see figure 5): • If Input Str... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.8.2 High Efficiency Mode, Transport Streams | For Transport Streams, the receiver knows a-priori the sync-byte configuration and O-UPL = 188 x 8 bits, therefore UPL and SYNC fields in the BBHEADER shall be re-used to transmit the ISSY field. The Mode Adaptation unit shall perform the following sequence of operations (see figure 6): • If Input Stream Synchronizatio... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.8.3 Normal Mode, GCS (excluding GSE carried as GCS) | See clause 5.1.7 for BBHEADER signalling. For GCS the input stream shall have no structure, or the structure shall not be known by the modulator. The Mode Adaptation unit shall perform the following sequence of operations (see figure 7): • Set UPL = 0D; set SYNC according to [1]: SYNC 0x00 − 0xB8 is reserved for transp... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.8.4 Normal Mode, GSE carried as GCS | See clause 5.1.7 for BBHEADER signalling. For GSE carried as GCS (see table 1), the first GSE packet shall always be aligned to the DATA FIELD (no UP-slicing allowed). ETSI ETSI TS 102 755 V1.1.1 (2023-02) 34 The Mode Adaptation unit shall perform the following sequence of operations (see Figure 8): • Set UPL = 0D; set... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.8.5 High Efficiency Mode, GSE | GSE variable-length or constant-length UPs may be transmitted in HEM. If UP-slicing is used, SYNCD shall be computed. If the GSE packets are not UP-sliced, the first packet shall be aligned to the beginning of the DATA FIELD and thus SYNCD shall always be set to 0D. The receiver may derive the length of the UPs from th... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.8.6 High Efficiency Mode, GFPS and GCS | These modes are not defined. |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.1.8.7 Normal Mode, TS/GS = 10 | This mode is not defined (see table 1 and clause 5.1.8.4). |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.2 Stream Adaptation | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.2.0 Overview | Stream Adaptation (see figures 2 and figure 10) provides: a) scheduling (for input mode 'B'), see clause 5.2.1; b) padding (see PADDING field and clause 5.2.2) to complete a constant length (Kbch bits) BBFRAME and/or to carry In-Band Signalling according to clause 5.2.3; c) scrambling (see clause 5.2.4) for energy disp... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.2.1 Scheduler | In order to generate the required L1-post-dynamic signalling information, the Scheduler shall decide exactly which cells of the final T2-signal will carry data belonging to which PLPs, as shown in figure 2 c). Although this operation has no effect on the data stream itself at this stage, the Scheduler shall define the ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.2.2 Padding | Kbch depends on the FEC rate, as reported in tables 7. Padding may be applied in circumstances when the user data available for transmission is not sufficient to completely fill a BBFRAME, or when an integer number of UPs has to be allocated in a BBFRAME. (Kbch-DFL-80) zero bits shall be appended after the DATA FIELD. ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.2.3 Use of the PADDING field for In-Band Signalling | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.2.3.0 Types and format | The PADDING field may also be used to carry In-Band Signalling. Two types of In-Band Signalling are defined: type A and type B. Future versions of the present document may define other types of In-Band signalling. The PADDING field may contain an In-Band Signalling block of type A only, or of type B only, or a block of... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.2.3.1 In-Band Type-A | An In-Band Signalling block carrying L1/L2 update information and co-scheduled information is defined as In-Band Type-A. When IN-BAND_ A_FLAG field in L1-post signalling, defined in clause 7.2.3, is set to '0', the In-Band Type-A is not carried in the PADDING field. When NUM_PLP (see clause 7.2.3.1) is greater than 1, ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.2.3.2 In-Band Type-B | For a PLP carrying TS or GFPS, an In-Band Type-B block shall carry additional information related to the Input Processing for the PLP containing the Type-B block. In particular it shall contain extra ISSY information, to enable faster initial acquisition, related to the BBFRAME carrying the Type-B block. The use of in-... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 5.2.4 BB scrambling | The complete BBFRAME shall be randomized. The randomization sequence shall be synchronous with the BBFRAME, starting from the MSB and ending after Kbch bits. The scrambling sequence shall be generated by the feedback shift register of figure 12. The polynomial for the Pseudo-Random Binary Sequence (PRBS) generator shal... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6 Bit-Interleaved Coding and Modulation | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.1 FEC encoding | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.1.0 Overview | This sub-system shall perform outer coding (BCH), inner coding (LDPC) and bit interleaving. The input stream shall be composed of BBFRAMEs and the output stream of FECFRAMEs. Each BBFRAME (Kbch bits) shall be processed by the FEC coding sub-system, to generate a FECFRAME (Nldpc bits). The parity check bits (BCHFEC) of ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.1.1 Outer encoding (BCH) | A t-error correcting BCH (Nbch, Kbch) code shall be applied to each BBFRAME to generate an error-protected packet. The BCH code parameters for Nldpc = 64 800 are given in table 7 a) and for Nldpc = 16 200 in table 7 b). The generator polynomial of the t error correcting BCH encoder is obtained by multiplying the first ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.1.2 Inner encoding (LDPC) | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.1.2.0 Overview | The LDPC encoder treats the output of the outer encoding, I = (, , . . . , ), as an information block of size = , and systematically encodes it onto a codeword Λ of size , where: Λ= , , , . . . , = ( , , . . . , , , , . . . ). ETSI ETSI TS 102 755 V1.1.1 (2023-... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.1.2.1 Inner coding for normal FECFRAME | The task of the encoder is to determine − parity bits ( , , . . . , ) for every block of information bits, ( , , . . . , ). The procedure is as follows: • Initialize = = =. . . = = 0 • Accumulate the first information bit, 0i , at parity bit addresses specified in the... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.1.2.2 Inner coding for short FECFRAME | BCH-coded bits shall be systematically encoded to generate bits as described in clause 6.1.2.1, replacing table 9 a) with table 9 b), the tables of annex A with the tables of annex B. Table 9 b): values for short frames Code Rate 1/4 36 1/3 30 2/5 27 1/2 25 3/5 18 2/3 15 3/4 12 4/5 10 5/6 8 |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.1.3 Bit Interleaver (for 16-QAM, 64-QAM and 256-QAM) | The output Λ of the LDPC encoder shall be bit interleaved, which consists of parity interleaving followed by column- twist interleaving. The parity interleaver output is denoted by U and the column-twist interleaver output by V. In the parity-interleaving part, parity bits are interleaved by: = for 0 ≤ < (inf... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.2 Mapping bits onto constellations | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.2.0 Overview | Each FECFRAME (which is a sequence of 64 800 bits for normal FECFRAME, or 16 200 bits for short FECFRAME), shall be mapped onto a coded and modulated FEC-block by first demultiplexing the input bits into parallel cell words and then mapping these cell words onto constellation values. The number of output data cells and... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.2.1 Bit to cell word de-multiplexer | The bit-stream vdi from the bit interleaver is de-multiplexed into Nsub-streams sub-streams, as shown in figure 15. The value of Nsub-streams is defined in table 13. Table 13: Number of sub-streams in demultiplexer Modulation Nldpc Number of sub-streams, Nsub-streams QPSK Any 2 16-QAM Any 8 64-QAM Any 12 256-QAM 64 800... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.2.2 Cell word mapping onto I/Q constellations | Each cell word (y0,q ... yηmod-1,q) from the de-multiplexer in clause 6.2.1 shall be modulated using either QPSK, 16-QAM, 64-QAM or 256-QAM constellations to give a constellation point zq prior to normalization. BPSK is only used for the L1 signalling (see clause 7.3.3.2) but the constellation mapping is specified here... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.3 Constellation Rotation and Cyclic Q Delay | When Constellation Rotation is used, the normalized cell values of each FEC-block F=(f0, f1, …, fNcells−1), coming from the constellation mapper (see clause 6.2.2) are rotated in the complex plane and the imaginary part cyclically delayed by one cell within a FEC-block. Ncells is the number of cells per FEC-block and i... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.4 Cell Interleaver | The pseudo-random Cell Interleaver (CI), which is illustrated in figure 18, shall uniformly spread the cells in the FEC codeword, to ensure in the receiver an uncorrelated distribution of channel distortions and interference along the FEC codewords, and shall differently "rotate" the interleaving sequence in each of th... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.5 Time Interleaver | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.5.0 Overview | The Time Interleaver (TI) shall operate at PLP level. The parameters of the time interleaving may be different for different PLPs within a T2-system. When time interleaving is not used for a PLP (i.e. when the L1-post signalling parameter TIME_IL_LENGTH is set to 0, see clause 7.2.3), the remainder of clause 6.5, and c... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.5.1 Mapping of Interleaving Frames onto one or more T2-frames | Each Interleaving Frame is either mapped directly onto one T2-frame or spread out over several T2-frames. The number of T2-frames in one Interleaving Frame, PI, is signalled in the L1post-configurable signalling by TIME_IL_LENGTH in conjunction with TIME_IL_TYPE. The length of the time-interleaving period TP shall not ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.5.2 Division of Interleaving Frames into Time Interleaving blocks | The Time Interleaver interleaves cells over one TI-block, which contains a dynamically variable integer number of FEC-blocks. In one Interleaving Frame there may be one or more TI-block(s). The number of TI-blocks in an Interleaving Frame, denoted by NTI, shall be an integer and is signalled in the L1-post-configurable... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.5.3 Interleaving of each TI-block | The TI shall store in the TI memories (one per PLP) the cells (dn,s,0,0, dn,s,0,1,…, dn,s,0,Ncells-1, dn,s,1,0, dn,s,1,1,…, dn,s,1,Ncells-1, …, dn,s,NFEC_TI(n,s)-1,0, dn,s, NFEC_TI(n,s)-1,1,…, dn,s,NFEC_TI(n,s)-1, Ncells-1) of the NFEC_TI(n,s) FEC-blocks from the output of the Cell Interleaver, where dn,s,r,q is the ou... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.5.4 Using the three time interleaving options with sub-slicing | In order to allow the maximum flexibility to select TI characteristics, the Interleaving Frames at the output of the Time Interleaver may be split into multiple sub-slices, as described in clause 8.3.6.3.3. The case where sub-slicing is used together with time-interleaving option (1) (where PI = 1 and NTI = 1 as define... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 6.5.5 PLPs for which time-interleaving is not used | If time interleaving is not used (i.e. TIME_IL_LENGTH = 0), the output of the Time Interleaver shall consist of the cells presented at the input in the same order and without modification. In this case, when the term Interleaving Frame is used elsewhere in the present document, it shall be taken to mean T2-frame. NOTE:... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.1 Introduction | This clause describes the Layer 1 (L1) signalling. The L1 signalling provides the receiver with a means to access Physical Layer Pipes within the T2-frames. Figure 25 illustrates the L1 signalling structure, which is split into three main sections: the P1 signalling, the L1-pre signalling and L1-post signalling. The pu... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2 L1 signalling data | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.0 Overview | All L1 signalling data, except for the dynamic L1-post signalling, shall remain unchanged for the entire duration of one super-frame. Hence any changes implemented to the current configuration (i.e. the contents of the L1-pre signalling or the configurable part of the L1-post signalling) shall always be done within the... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.1 P1 Signalling data | The P1 symbol has the capability to convey 7 bits for signalling. Since the preamble (both P1 and P2 symbols) may have different formats, the main use of the P1 signalling is to identify the preamble itself. The information it carries is of two types: the first type (associated with the S1 bits of the P1) is needed to ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.2 L1-pre signalling data | Figure 26 illustrates the signalling fields of the L1-pre signalling, followed by the detailed definition of each field. Figure 26: The signalling fields of L1-pre signalling ETSI ETSI TS 102 755 V1.1.1 (2023-02) 68 TYPE: This 8-bit field indicates the types of the Tx input streams carried within the current super-fram... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.3 L1-post signalling data | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.3.0 Overview | The L1-post signalling contains parameters which provide sufficient information for the receiver to decode the desired Physical Layer Pipe(s). The L1-post signalling further consists of two types of parameters, configurable and dynamic, plus an optional extension field. The configurable parameters shall always remain t... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.3.1 Configurable L1-post signalling | Figure 28 illustrates the signalling fields of the configurable L1-post signalling, followed by the detailed definition of each field. Figure 28: The signalling fields of configurable L1-post signalling ETSI ETSI TS 102 755 V1.1.1 (2023-02) 73 SUB_SLICES_PER_FRAME: This 15-bit field indicates Nsub-slices_total, the tot... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.3.2 Dynamic L1-post signalling | The dynamic L1-post signalling is illustrated in figure 29, followed by the detailed definition of each field. Figure 29: The signalling fields of the dynamic L1-post signalling FRAME_IDX: This 8-bit field is the index of the current T2-frame within a super-frame. The index of the first frame of the super-frame shall b... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.3.3 Repetition of L1-post-dynamic data | To obtain increased robustness for the dynamic part of L1-post signalling, the information may be repeated in the preambles of two successive T2-frames. The use of this repetition is signalled in L1-pre parameter L1_REPETITION_FLAG. If the flag is set to '1', dynamic L1-post signalling for the current and next T2-frame... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.3.4 L1-post extension field | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.3.4.0 Overview | The L1-post extension field allows for the possibility for future expansion of the L1 signalling. Its presence is indicated by the L1-pre field L1_POST_EXTENSION. If it is present, the L1-post extension shall contain one or more L1-post extension blocks. The syntax of each block shall be as shown in table38. Table 38: ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.3.4.1 Padding L1-post extension blocks | L1-post extension blocks of type '11111111' shall contain padding. They may be of any desired length, subject to the capacity of the P2 symbols. The contents of the L1_EXT_BLOCK_DATA field are sometimes used for bias-balancing (see clause 7.2.3.7). |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.3.5 CRC for the L1-post signalling | A 32-bit error detection code is applied to the entire L1-post signalling including the configurable and the dynamic parts for the current T2-frame, the dynamic part for the next T2-frame, if present, and the L1-post extension field, if present. The location of the CRC field can be found from the length of the L1-post ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.3.6 L1 padding | This variable-length field is inserted following the L1-post CRC field to ensure that multiple LDPC blocks of the L1-post signalling have the same information size when the L1-post signalling is segmented into multiple blocks and these blocks are separately encoded. Details of how to determine the length of this field ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.2.3.7 L1 bias-balancing bits | As described in clause 7.1, some reserved fields and part of the L1 extension field, if any, are sometimes used for bias-balancing and may be set according to the algorithm described in this clause. Other algorithms may also be used for setting these bits. L1 bias-balancing bits are used to reduce the imbalance in the ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3 Modulation and error correction coding of the L1 data | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.1 Overview | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.1.1 Error correction coding and modulation of the L1-pre signalling | The L1-pre signalling is protected by a concatenation of BCH outer code and LDPC inner code. The L1-pre signalling bits have a fixed length and they shall be first BCH-coded, where the BCH parity check bits of the L1-pre signalling shall be appended to the L1-pre signalling. The concatenated L1-pre-signalling and BCH p... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.1.2 Error correction coding and modulation of the L1-post signalling | The number of L1-post signalling bits is variable, and the bits shall be transmitted over one or multiple 16K LDPC blocks depending on the length of the L1-post signalling. The number of LDPC blocks for the L1-post signalling, Npost_FEC_block shall be determined as follows: " _ _#" $ = %__ % , where x ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.2 Scrambling and FEC encoding | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.2.1 Scrambling of L1-post information bits | When the L1_POST_SCRAMBLED bit is set to a '1', all of the bits of each L1-post block with information size of Ksig shall be scrambled using the same scrambling sequence as for BBFRAMES (see clause 5.2.4). NOTE: This feature was not included in ETSI EN 302 755 V1.1.1 [i.7] and V1.2.1 [i.8] - therefore it should not be ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.2.2 Zero-padding of BCH information bits | Ksig bits defined in clauses 7.3.1.1 and 7.3.1.2, and when required, scrambled according to clause 7.3.2.1, shall be encoded into a 16K (Nldpc = 16 200) LDPC codeword after BCH encoding. If the Ksig is less than the number of BCH information bits (= Kbch) for a given code rate, the BCH code will be shortened. A part of... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.2.3 BCH encoding | The Kbch information bits (including the Kbch − Ksig zero-padding bits) shall first be BCH-coded according to clause 6.1.1 to generate Nbch = Kldpc output bits (i0 … iNbch − 1). |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.2.4 LDPC encoding | The Nbch = Kldpc output bits (i0 … iNbch-1) from the BCH encoder, including the (Kbch − Ksig) zero-padding bits and the (Kldpc − Kbch) BCH parity bits form the Kldpc information bits I = (i0, i1, …, iKldpc-1) for the LDPC encoder. The LDPC encoder shall systematically encode the Kldpc information bits onto a codeword Λ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.2.5 Puncturing of LDPC parity bits | When the shortening is applied to encoding of the signalling bits, some LDPC parity bits shall be punctured after the LDPC encoding. These punctured bits shall not be transmitted. ETSI ETSI TS 102 755 V1.1.1 (2023-02) 86 All Nldpc − Kldpc LDPC parity bits, denoted by {p0, p1, …, pNldpc−Kldpc−1}, are divided into Qldpc ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.2.6 Removal of zero-padding bits | The (Kbch - Ksig) zero-padding bits are removed and shall not be transmitted. This leaves a codeword consisting of the Ksig information bits, followed by the 168 BCH parity bits and (Nldpc - Kldpc - Npunc) LDPC parity bits. |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.2.7 Bit interleaving for L1-post signalling | When 16-QAM or 64-QAM modulation is used for the L1-post signalling, the LDPC codeword of length Npost, consisting of Ksig information bits, 168 BCH parity bits, and (9 000 - Npunc) LDPC parity bits, shall be bit-interleaved using a block interleaver. The configuration of the bit interleaver for each modulation is spec... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.3 Mapping bits onto constellations | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.3.0 Overview | Each bit-interleaved LDPC codeword shall be mapped onto constellations. Each bit of the L1-pre signalling is mapped directly onto a BPSK constellation according to clause 7.3.3.2, whereas the L1-post signalling is first demultiplexed into cell words according to clause 7.3.3.1 and then the cell words are mapped onto co... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.3.1 Demultiplexing of L1-post signalling | Each bit-interleaved punctured and shortened LDPC codeword, a sequence of Npost bits, = ( . . . ),where Npost = Ksig + 168 + 9 000 − Npunc, shall be mapped onto constellations by first de-multiplexing the input bits into parallel cell words and then mapping these cell words onto constellation values. The number... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.3.2 Mapping onto I/Q constellations | The bits of the L1-pre signalling y0,q and the cell words of the L1-post signalling [y0,q ... yηmod-1,q] are mapped onto constellations f_preq and f_postq respectively according to clause 6.2.2, where q is the index of the cells within each bit-interleaved LDPC codeword. For the L1-pre signalling, 0 ≤ q < 1 840, and fo... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 7.3.3.3 Modification of L1 signalling constellations by L1-ACE algorithm | To further reduce the bias in the L1 signalling, if the T2_VERSION field (see clause 7.2.2) is set to a value greater than '0000', a small modification of the modulated L1 cells shall be applied. This clause describes the algorithm to be applied to all of the BPSK cells of the L1-pre signalling, and to all of the cells... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8 Frame Builder | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.0 Overview | This clause defines the Frame Builder functions that always apply for a T2-system with a single RF channel. Some of the Frame Builder functions for a TFS system with multiple RF channels differ from those defined in this clause. The TFS specific Frame Builder functions are defined in annex E. Other Frame Builder functi... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.1 Frame structure | The DVB-T2 frame structure is shown in figure 36. At the top level, the frame structure consists of super-frames, which are divided into T2-frames and these are further divided into OFDM symbols. The super-frame may in addition have FEF parts (see clause 8.4). T2-frame 0 T2-frame 1 T2-frame 2 T2-frame NT2-1 Super-frame... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.2 Super-frame | A super-frame can carry T2-frames and may also have FEF parts, see figure 37. ... FEF length FEF interval A + B + C = NT2 T2-frame A B C FEF part T2-frame ... T2-frame FEF part T2-frame ... T2-frame FEF part T2-frame A = B = C = FEF interval FEF length FEF interval FEF interval FEF length Figure 37: The super-frame, in... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3 T2-frame | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.0 Overview | The T2-frame comprises one P1 preamble symbol, followed by one or more P2 preamble symbols, followed by a configurable number of data symbols. In certain combinations of FFT size, Guard Interval and Pilot Pattern (see clause 9.2.7), the last data symbol shall be a Frame-Closing Symbol. The details of the T2-frame struc... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.1 Duration of the T2-frame | The beginning of the first preamble symbol (P1) marks the beginning of the T2-frame. The number of P2 symbols NP2 is determined by the FFT size as given in table 52, whereas the number of data symbols Ldata in the T2-frame is a configurable parameter signalled in the L1-pre signalling, i.e. Ldata = NUM_DATA_SYMBOLS. Th... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.2 Capacity and structure of the T2-frame | The Frame Builder shall map the cells from both the Time Interleaver (for the PLPs) and the constellation mapper (for the L1-pre and L1-post signalling) onto the data cells xm,l,p of each OFDM symbol in each frame, where: • m is the T2-frame number; • l is the index of the symbol within the frame, starting at 0 for the... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.3 Signalling of the T2-frame structure and PLPs | The configuration of the T2-frame structure is signalled by the L1-pre and L1-post signalling (see clause 7.2). The locations of the PLPs themselves within the T2-frame can change dynamically from T2-frame to T2-frame, and this is signalled both in the dynamic part of the L1-post signalling in P2 (see clause 7.2.3.2), ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.4 Overview of the T2-frame mapping | The slices and sub-slices of the PLPs, the Auxiliary Streams and dummy cells are mapped onto the symbols of the T2-frame as illustrated in figure 40. The T2-frame starts with a P1 symbol followed by NP2 P2 symbols. The L1-pre and L1-post signalling are first mapped onto P2 symbol(s) (see clause 8.3.5). After that, the ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.5 Mapping of L1 signalling information onto P2 symbol(s) | Coded and modulated L1-pre and L1-post cells for T2-frame m are mapped onto the P2 symbol(s) as follows: 1) L1-pre cells are mapped onto the active cells of P2 symbol(s) in row-wise zig-zag manner as illustrated in figure 41 by the blue blocks and described in the following equation: , for 0 ≤ < and 0 ≤ < ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.6 Mapping the PLPs onto the T2-frames | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.6.0 Overview | After the L1 data has been mapped onto the P2 symbol(s), bias-balancing cells may be added, and the remaining active data cells xm,l,p in the P2 symbol(s) and data symbols are available for PLPs. PLPs are classified into 3 types, signalled in L1-post signalling field PLP_TYPE; Common PLP, Data PLP of Type 1 and Data PL... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.6.1 Allocating the cells of the Interleaving Frames to the T2-frames | If the Interleaving Frame for a given PLP is mapped directly onto one T2-frame (see clause 6.5), then the cells to be allocated to the T2-frame shall be all of the cells of the corresponding Interleaving Frame from the output of the Time Interleaver. In general, the Interleaving Frame for PLP i will be mapped onto PI(i... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.6.2 Addressing of OFDM cells | A one-dimensional addressing scheme (0 ... DPLP − 1) is defined for the active data cells that are not used for L1 signalling. The addressing scheme defines the order in which the cells from the sub-slices of the PLPs are allocated to the active data cells, and is also used to signal the locations of the sub-slices of ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.6.3 Mapping the PLPs onto the Data cell addresses | |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.6.3.0 Overview | The allocation of slices and sub-slices to the T2-frames is done by the Scheduler. The Scheduler may use any method to perform the allocation and may map the PLPs onto the T2-frame in any order subject to the requirements in the following clauses and provided also that the locations of the cells of the PLPs are as desc... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.6.3.1 Insertion of bias-balancing cells | If the bias-balancing bits (see clause 7.2.3.7) were insufficient to completely balance the bias in the L1 signalling, a peak may result in the time domain signal of the P2 symbols. If the limits on the Tone-Reservation algorithm for PAPR reduction (see clause 9.6.2) mean that it will be unable to reduce this peak to a... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.6.3.2 Mapping the Common and Type-1 PLPs onto the T2-frame | The cells of the Common PLPs, if any, shall be mapped onto the first part of the frame (i.e. they shall have lower cell addresses than for the other types of PLP), but shall always be after the bias-balancing cells, if any. The cells of any one Common PLP for a particular T2-frame shall be mapped sequentially onto a si... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.6.3.3 Mapping the Type-2 PLPs onto the T2-frame | The cells of each Type-2 PLP that are allocated to a particular T2-frame shall be divided into Nsub-slices sub-slices, where Nsub-slices (in the non-TFS case) is equal to Nsub-slices_total, signalled by SUB_SLICES_PER_FRAME in the L1-post-configurable signalling. The number of sub-slices per T2-frame, Nsub-slices, the ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.7 Auxiliary Stream insertion | Following the Type-2 PLPs, one or more Auxiliary Streams may be added. Each Auxiliary Stream consists of a sequence of Di,aux cell values xm,l,p in each T2-frame, where i is the Auxiliary Stream index. The cell values shall have the same mean power as the data cells of the Data PLPs, i.e. E(xm,l,p. xm,l,p *) = 1, but a... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.8 Dummy cell insertion | If the L1 signalling, bias-balancing cells, PLPs and Auxiliary Streams do not exactly fill the Ctot active cells in one T2-frame, dummy cells shall be inserted in the remaining Ndummy cells (see clause 8.3.6.3), where: dummy = plp − biasCellsActive * + ∑ ,common /common + ∑ , / + ∑ , + ∑ ,aux /)*+ ... |
7b4ea1ddda2445fed694673e017a5e51 | 102 755 | 8.3.9 Insertion of unmodulated cells in the Frame-Closing Symbol | When a Frame-Closing Symbol is used (see clauses 8.3.2 and 9.2.7), some of its data cells carry no modulation in order to maintain constant symbol power in the presence of a higher pilot density. The last NFC − CFC cells of the Frame-Closing Symbol, ( ,2, . .. ,2, ), shall all be set to 0 + j0. |
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