ETSI EN 300 744 V1.2.1 (1999-07)
`
`European Standard (Telecommunications series)
`
`Digital Video Broadcasting (DVB);
`Framing structure, channel coding and modulation for
`digital terrestrial television
`
`European Broadcasting Union
`
`Union Européenne de Radio-Télévision
`
`EBU
`UER
`
`1
`
`LGE 1005
`
`

`

`2
`
`ETSI EN 300 744 V1.2.1 (1999-07)
`
`Reference
`REN/JTC-DVB-87 (6w000ioo.PDF)
`
`Keywords
`DVB, digital, video, broadcasting, terrestrial,
`MPEG, TV, audio, data
`
`ETSI
`
`Postal address
`F-06921 Sophia Antipolis Cedex - FRANCE
`
`Office address
`650 Route des Lucioles - Sophia Antipolis
`Valbonne - FRANCE
`Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16
`Siret N° 348 623 562 00017 - NAF 742 C
`Association à but non lucratif enregistrée à la
`Sous-Préfecture de Grasse (06) N° 7803/88
`
`Internet
`secretariat@etsi.fr
`Individual copies of this ETSI deliverable
`can be downloaded from
`http://www.etsi.org
`If you find errors in the present document, send your
`comment to: editor@etsi.fr
`
`Copyright Notification
`
`No part may be reproduced except as authorized by written permission.
`The copyright and the foregoing restriction extend to reproduction in all media.
`
`© European Telecommunications Standards Institute 1999.
`© European Broadcasting Union 1999.
`All rights reserved.
`
`ETSI
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`3
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`ETSI EN 300 744 V1.2.1 (1999-07)
`
`Contents
`
`Intellectual Property Rights ............................................................................................................................... 5
`
`Foreword ............................................................................................................................................................ 5
`
`1
`
`2
`
`3
`3.1
`3.2
`3.3
`
`Scope........................................................................................................................................................ 6
`
`References ............................................................................................................................................... 6
`
`Definition, symbols and abbreviations .................................................................................................... 6
`Definition........................................................................................................................................................... 6
`Symbols ............................................................................................................................................................. 7
`Abbreviations..................................................................................................................................................... 8
`
`4
`4.1
`4.2
`4.3
`4.3.1
`4.3.2
`4.3.3
`4.3.4
`4.3.4.1
`4.3.4.2
`4.3.5
`4.4
`4.5
`4.5.1
`4.5.2
`4.5.3
`4.5.4
`4.5.5
`4.6
`4.6.1
`4.6.2
`4.6.2.1
`4.6.2.2
`4.6.2.3
`4.6.2.4
`4.6.2.5
`4.6.2.6
`4.6.2.7
`4.6.2.8
`4.6.2.9
`4.6.2.10
`4.6.3
`4.7
`4.8
`4.8.1
`4.8.2
`4.8.3
`
`Baseline system ....................................................................................................................................... 8
`General considerations....................................................................................................................................... 8
`Interfacing........................................................................................................................................................ 10
`Channel coding and modulation....................................................................................................................... 10
`Transport multiplex adaptation and randomization for energy dispersal ................................................... 10
`Outer coding and outer interleaving ........................................................................................................... 11
`Inner coding ............................................................................................................................................... 13
`Inner interleaving ....................................................................................................................................... 14
`Bit-wise interleaving............................................................................................................................. 14
`Symbol interleaver................................................................................................................................ 18
`Signal constellations and mapping ............................................................................................................. 20
`OFDM frame structure..................................................................................................................................... 24
`Reference signals ............................................................................................................................................. 26
`Functions and derivation ............................................................................................................................ 26
`Definition of reference sequence................................................................................................................ 26
`Location of scattered pilot cells ................................................................................................................. 27
`Location of continual pilot carriers ............................................................................................................ 28
`Amplitudes of all reference information..................................................................................................... 28
`Transmission Parameter Signalling (TPS) ....................................................................................................... 29
`Scope of the TPS........................................................................................................................................ 29
`TPS transmission format ............................................................................................................................ 30
`Initialization.......................................................................................................................................... 30
`Synchronization .................................................................................................................................... 30
`TPS length indicator ............................................................................................................................. 30
`Frame number....................................................................................................................................... 31
`Constellation......................................................................................................................................... 31
`Hierarchy information .......................................................................................................................... 31
`Code rates ............................................................................................................................................. 31
`Guard Intervals ..................................................................................................................................... 32
`Transmission mode............................................................................................................................... 32
`Error protection of TPS ........................................................................................................................ 32
`TPS modulation.......................................................................................................................................... 33
`Number of RS-packets per OFDM super-frame .............................................................................................. 33
`Spectrum characteristics and spectrum mask ................................................................................................... 34
`Spectrum characteristics............................................................................................................................. 34
`Out-of-band spectrum mask (for 8 MHz channels) .................................................................................... 35
`Centre frequency of RF signal (for 8 MHz UHF channels)........................................................................ 38
`
`ETSI
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`4
`
`ETSI EN 300 744 V1.2.1 (1999-07)
`
`Annex A (informative):
`
`Simulated system performance for 8 MHz channels ................................. 39
`
`Annex B (informative):
`
`Definition of P1 and F1 .................................................................................. 41
`
`Annex C (informative):
`
`Interleaving example..................................................................................... 43
`
`Annex D (informative):
`
`Guidelines to implementation of the emitted signal .................................. 44
`
`D.1 Use of the FFT ....................................................................................................................................... 44
`
`D.2 Choice of "baseband" centre frequency................................................................................................. 45
`
`D.3 Other potential difficulties..................................................................................................................... 45
`
`Annex E (normative):
`
`Values for 6 MHz and 7 MHz channels ...................................................... 46
`
`History.............................................................................................................................................................. 49
`
`ETSI
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`5
`
`ETSI EN 300 744 V1.2.1 (1999-07)
`
`Intellectual Property Rights
`
`IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
`pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
`in SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect
`of ETSI standards", which is available free of charge from the ETSI Secretariat. Latest updates are available on the
`ETSI Web server (http://www.etsi.org/ipr).
`
`Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
`can be given as to the existence of other IPRs not referenced in SR 000 314 (or the updates on the ETSI Web server)
`which are, or may be, or may become, essential to the present document.
`
`Foreword
`
`This European Standard (Telecommunications series) has been produced by the Joint Technical Committee (JTC)
`Broadcast of the European Broadcasting Union (EBU), Comité Européen de Normalisation ELECtrotechnique
`(CENELEC) and the European Telecommunications Standards Institute (ETSI).
`
`NOTE:
`
`The EBU/ETSI JTC Broadcast was established in 1990 to co-ordinate the drafting of standards in the
`specific field of broadcasting and related fields. Since 1995 the JTC Broadcast became a tripartite body
`by including in the Memorandum of Understanding also CENELEC, which is responsible for the
`standardization of radio and television receivers. The EBU is a professional association of broadcasting
`organizations whose work includes the co-ordination of its members' activities in the technical, legal,
`programme-making and programme-exchange domains. The EBU has active members in about 60
`countries in the European broadcasting area; its headquarters is in Geneva.
`
`European Broadcasting Union
`CH-1218 GRAND SACONNEX (Geneva)
`Switzerland
`Tel:
`+41 22 717 21 11
`Fax:
`+41 22 717 24 81
`
`Digital Video Broadcasting (DVB) Project
`
`Founded in September 1993, the DVB Project is a market-led consortium of public and private sector organizations in
`the television industry. Its aim is to establish the framework for the introduction of MPEG-2 based digital television
`services. Now comprising over 200 organizations from more than 25 countries around the world, DVB fosters
`market-led systems, which meet the real needs, and economic circumstances, of the consumer electronics and the
`broadcast industry.
`
`National transposition dates
`
`Date of adoption of this EN:
`
`Date of latest announcement of this EN (doa):
`
`Date of latest publication of new National Standard
`or endorsement of this EN (dop/e):
`
`Date of withdrawal of any conflicting National Standard (dow):
`
`11 June 1999
`
`30 September 1999
`
`31 March 2000
`
`31 March 2000
`
`ETSI
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`

`6
`
`ETSI EN 300 744 V1.2.1 (1999-07)
`
`1
`
`Scope
`
`The present document describes a baseline transmission system for digital terrestrial TeleVision (TV) broadcasting. It
`specifies the channel coding/modulation system intended for digital multi-programme LDTV/SDTV/EDTV/HDTV
`terrestrial services.
`
`The scope is as follows:
`
`-
`
`-
`
`-
`
`it gives a general description of the Baseline System for digital terrestrial TV;
`
`it identifies the global performance requirements and features of the Baseline System, in order to meet the service
`quality targets;
`
`it specifies the digitally modulated signal in order to allow compatibility between pieces of equipment developed
`by different manufacturers. This is achieved by describing in detail the signal processing at the modulator side,
`while the processing at the receiver side is left open to different implementation solutions.
`However, it is necessary in this text to refer to certain aspects of reception.
`
`2
`
`References
`
`The following documents contain provisions which, through reference in this text, constitute provisions of the present
`document.
`
`• References are either specific (identified by date of publication, edition number, version number, etc.) or
`non-specific.
`
`• For a specific reference, subsequent revisions do not apply.
`
`• For a non-specific reference, the latest version applies.
`
`• A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same
`number.
`
`[1]
`
`[2]
`
`[3]
`
`ISO/IEC 13818: "Information technology - Generic coding of moving pictures and associated
`audio information - Part 1 (Systems), 2 (Video), 3 (Audio)".
`
`EN 300 421: "Digital Video Broadcasting (DVB); Framing structure, channel coding and
`modulation for 11/12 GHz satellite services".
`
`EN 300 429: "Digital Video Broadcasting (DVB); Framing structure, channel coding and
`modulation for cable systems".
`
`3
`
`Definition, symbols and abbreviations
`
`3.1
`
`Definition
`
`For the purposes of the present document, the following definition applies:
`
`constraint length: number of delay elements +1 in the convolutional coder
`
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`ETSI EN 300 744 V1.2.1 (1999-07)
`
`3.2
`
`Symbols
`
`For the purposes of the present document, the following symbols apply:
`
`A(e)
`ae,w
`α
`
`output vector from inner bit interleaver e
`bit number w of inner bit interleaver output stream e
`constellation ratio which determines the QAM constellation for the modulation for hierarchical
`transmission
`input vector to inner bit interleaver e
`B(e)
`be,w
`bit number w of inner bit interleaver input steam e
`output bit number do of demultiplexed bit stream number e of the inner interleaver demultiplexer
`be,do
`complex cell for frame m in OFDM symbol l at carrier k
`cm,l,k
`C'k
`Complex modulation for a reference signal at carrier k
`Complex modulation for a TPS signal at carrier k in symbol l
`C'l,k
`Carrier-to-noise ratio
`C/N
`∆
`time duration of the guard interval
`dfree
`convolutional code free distance
`centre frequency of the emitted signal
`fc
`convolutional code Generator polynomials
`G1, G2
`Reed-Solomon code generator polynomial
`g(x)
`BCH code generator polynomial
`h(x)
`inner symbol interleaver permutation
`H(q)
`He(w)
`inner bit interleaver permutation
`priority stream index
`i
`Interleaving depth of the outer convolutional interleaver
`I
`I0,I1,I2,I3,I4,I5 inner Interleavers
`j
`branch index of the outer interleaver
`k
`carrier number index in each OFDM symbol
`K
`number of active carriers in the OFDM symbol
`Kmin, Kmax
`carrier number of the lower and largest active carrier respectively in the OFDM signal
`l
`OFDM symbol number index in an OFDM frame
`m
`OFDM frame number index
`m'
`OFDM super-frame number index
`M
`convolutional interleaver branch depth for j = 1, M = N/I
`n
`transport stream sync byte number
`N
`length of error protected packet in bytes
`Nmax
`inner symbol interleaver block size
`p
`scattered pilot insertion index
`p(x)
`RS code field generator polynomial
`Pk(f)
`Power spectral density for carrier k
`P(n)
`interleaving Pattern of the inner symbol interleaver
`ri
`code rate for priority level i
`si
`TPS bit index
`t
`number of bytes which can be corrected by the Reed-Solomon decoder
`T
`elementary Time period
`TS
`duration of an OFDM symbol
`TF
`Time duration of a frame
`TU
`Time duration of the useful (orthogonal) part of a symbol, without the guard interval
`u
`bit numbering index
`v
`number of bits per modulation symbol
`wk
`value of reference PRBS sequence applicable to carrier k
`xdi
`input bit number di to the inner interleaver demultiplexer
`x'di
`high priority input bit number di to the inner interleaver demultiplexer
`x"di
`low priority input bit number di to the inner interleaver demultiplexer
`Y
`output vector from inner symbol interleaver
`Y'
`intermediate vector of inner symbol interleaver
`yq
`bit number q of output from inner symbol interleaver
`y'q
`bit number q of intermediate vector of inner symbol interleaver
`z
`complex modulation symbol
`
`ETSI
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`8
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`ETSI EN 300 744 V1.2.1 (1999-07)
`
`3.3
`
`Abbreviations
`
`For the purposes of the present document, the following abbreviations apply:
`
`ACI
`AFC
`BCH
`BER
`D/A
`DBPSK
`DFT
`DVB
`DVB-T
`EDTV
`FEC
`FFT
`FIFO
`HDTV
`HEX
`HP
`IF
`IFFT
`LDTV
`LO
`LP
`LSB
`MPEG
`MSB
`MUX
`NICAM
`OCT
`OFDM
`PAL
`PCR
`PID
`PRBS
`QAM
`QEF
`QPSK
`RF
`RS
`SDTV
`SECAM
`SFN
`TPS
`TV
`UHF
`VHF
`
`Adjacent Channel Interference
`Automatic Frequency Control
`Bose - Chaudhuri - Hocquenghem code
`Bit Error Ratio
`Digital-to-Analogue converter
`Differential Binary Phase Shift Keying
`Discrete Fourier Transform
`Digital Video Broadcasting
`DVB-Terrestrial
`Enhanced Definition TeleVision
`Forward Error Correction
`Fast Fourier Transform
`First-In, First-Out shift register
`High Definition TeleVision
`HEXadecimal notation
`High Priority bit stream
`Intermediate Frequency
`Inverse Fast Fourier Transform
`Limited Definition TeleVision
`Local Oscillator
`Low Priority bit stream
`Least Significant Bit
`Moving Picture Experts Group
`Most Significant Bit
`MUltipleX
`Near-Instantaneous Companded Audio Multiplex
`OCTal notation
`Orthogonal Frequency Division Multiplexing
`Phase Alternating Line
`Program Clock Reference
`Program IDentifier
`Pseudo-Random Binary Sequence
`Quadrature Amplitude Modulation
`Quasi Error Free
`Quaternary Phase Shift Keying
`Radio Frequency
`Reed-Solomon
`Standard Definition TeleVision
`Système Sequentiel Couleur A Mémoire
`Single Frequency Network
`Transmission Parameter Signalling
`TeleVision
`Ultra-High Frequency
`Very-High Frequency
`
`4
`
`Baseline system
`
`4.1
`
`General considerations
`
`The system is defined as the functional block of equipment performing the adaptation of the baseband TV signals from
`the output of the MPEG-2 transport multiplexer, to the terrestrial channel characteristics. The following processes shall
`be applied to the data stream (see figure 1):
`
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`9
`
`ETSI EN 300 744 V1.2.1 (1999-07)
`
`-
`
`-
`
`-
`
`-
`
`-
`
`transport multiplex adaptation and randomization for energy dispersal;
`
`outer coding (i.e. Reed-Solomon code);
`
`outer interleaving (i.e. convolutional interleaving);
`
`inner coding (i.e. punctured convolutional code);
`
`inner interleaving;
`
`- mapping and modulation;
`
`- Orthogonal Frequency Division Multiplexing (OFDM) transmission.
`
`The system is directly compatible with MPEG-2 coded TV signals ISO/IEC 13818 [1].
`
`Since the system is being designed for digital terrestrial television services to operate within the existing VHF and UHF
`(see note) spectrum allocation for analogue transmissions, it is required that the System provides sufficient protection
`against high levels of Co-Channel Interference (CCI) and Adjacent-Channel Interference (ACI) emanating from existing
`PAL/SECAM/NTSC services. It is also a requirement that the System allows the maximum spectrum efficiency when
`used within the VHF and UHF bands; this requirement can be achieved by utilizing Single Frequency Network (SFN)
`operation.
`
`NOTE:
`
`The OFDM system in the present document is specified for 8 MHz, 7 MHz and 6 MHz channel spacing.
`The basic specification is the same for the three bandwidths except for the parameter elementary period T,
`which is unique for the respective bandwidths. From an implementation point of view the elementary
`period T can normally be seen as the inverse of the nominal system clock rate. By adjusting the system
`clock rate the bandwidth and bit rate are modified accordingly.
`
`To achieve these requirements an OFDM system with concatenated error correcting coding is being specified.
`To maximize commonality with the Satellite baseline specification (see EN 300 421 [2]) and Cable baseline
`specifications (see EN 300 429 [3]) the outer coding and outer interleaving are common, and the inner coding is
`common with the Satellite baseline specification. To allow optimal trade off between network topology and frequency
`efficiency, a flexible guard interval is specified. This will enable the system to support different network configurations,
`such as large area SFN and single transmitter, while keeping maximum frequency efficiency.
`
`Two modes of operation are defined: a "2K mode" and an "8K mode". The "2K mode" is suitable for single transmitter
`operation and for small SFN networks with limited transmitter distances. The "8K mode" can be used both for single
`transmitter operation and for small and large SFN networks.
`
`The system allows different levels of QAM modulation and different inner code rates to be used to trade bit rate versus
`ruggedness. The system also allows two level hierarchical channel coding and modulation, including uniform and multi-
`resolution constellation. In this case the functional block diagram of the system shall be expanded to include the
`modules shown dashed in figure 1. The splitter separates the incoming transport stream into two independent MPEG
`transport streams, referred to as the high-priority and the low-priority stream. These two bitstreams are mapped onto the
`signal constellation by the Mapper and Modulator which therefore has a corresponding number of inputs.
`
`To guarantee that the signals emitted by such hierarchical systems may be received by a simple receiver the hierarchical
`nature is restricted to hierarchical channel coding and modulation without the use of hierarchical source coding.
`
`A programme service can thus be "simulcast" as a low-bit-rate, rugged version and another version of higher bit rate and
`lesser ruggedness. Alternatively, entirely different programmes can be transmitted on the separate streams with different
`ruggedness. In either case, the receiver requires only one set of the inverse elements: inner de-interleaver, inner decoder,
`outer de-interleaver, outer decoder and multiplex adaptation. The only additional requirement thus placed on the
`receiver is the ability for the demodulator/de-mapper to produce one stream selected from those mapped at the sending
`end.
`
`The price for this receiver economy is that reception can not switch from one layer to another (e.g. to select the more
`rugged layer in the event of reception becoming degraded) while continuously decoding and presenting pictures and
`sound. A pause is necessary (e.g. video freeze frame for approximately 0,5 seconds, audio interruption for
`approximately 0,2 seconds) while the inner decoder and the various source decoders are suitably reconfigured and
`reacquire lock.
`
`ETSI
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`10
`
`ETSI EN 300 744 V1.2.1 (1999-07)
`
` Figure 1: Functional block diagram of the System
`
`4.2
`
`Interfacing
`
`The Baseline System as defined in the present document is delimited by the following interfaces:
`
`Table 1: Interfaces for the Baseline System
`
`Location
`Transmit Station
`
`Receive Installation
`
`Interface
`Input
`Output
`Input
`Output
`
`Interface type
`MPEG-2 transport stream(s) multiplex
`RF signal
`RF
`MPEG-2 transport stream multiplex
`
`Connection
`from MPEG-2 multiplexer
`to aerial
`from aerial
`to MPEG-2 demultiplexer
`
`4.3
`
`Channel coding and modulation
`
`4.3.1
`
`Transport multiplex adaptation and randomization for energy
`dispersal
`
`The System input stream shall be organized in fixed length packets (see figure 3), following the MPEG-2 transport
`multiplexer. The total packet length of the MPEG-2 transport multiplex (MUX) packet is 188 bytes.
`This includes 1 sync-word byte (i.e. 47HEX). The processing order at the transmitting side shall always start from the
`MSB (i.e. "0") of the sync-word byte (i.e. 01 000 111). In order to ensure adequate binary transitions, the data of the
`input MPEG-2 multiplex shall be randomized in accordance with the configurations depicted in figure 2.
`
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`11
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`ETSI EN 300 744 V1.2.1 (1999-07)
`
`Figure 2: Scrambler/descrambler schematic diagram
`
`The polynomial for the Pseudo Random Binary Sequence (PRBS) generator shall be (see note):
`
`1 + X14 + X15
`
`NOTE:
`
`The polynomial description given here is in the form taken from the Satellite baseline specification
`EN 300 421 [2]. Elsewhere, in both the Satellite baseline specification and in the present document, a
`different polynomial notation is used which conforms with the standard textbook of Peterson and Weldon
`(Error correcting codes, second edition, MIT Press, 1972).
`
`Loading of the sequence "100101010000000" into the PRBS registers, as indicated in figure 2, shall be initiated at the
`start of every eight transport packets. To provide an initialization signal for the descrambler, the MPEG-2 sync byte of
`the first transport packet in a group of eight packets is bit-wise inverted from 47HEX (SYNC) to B8HEX (SYNC).
`This process is referred to as "transport multiplex adaptation" (see figure 3b).
`
`The first bit at the output of the PRBS generator shall be applied to the first bit (i.e. MSB) of the first byte following the
`inverted MPEG-2 sync byte (i.e. B8HEX). To aid other synchronization functions, during the MPEG-2 sync bytes of the
`subsequent 7 transport packets, the PRBS generation shall continue, but its output shall be disabled, leaving these bytes
`unrandomized. Thus, the period of the PRBS sequence shall be 1 503 bytes.
`
`The randomization process shall be active also when the modulator input bit-stream is non-existent, or when it is
`non-compliant with the MPEG-2 transport stream format (i.e. 1 sync byte + 187 packet bytes).
`
`4.3.2
`
`Outer coding and outer interleaving
`
`The outer coding and interleaving shall be performed on the input packet structure (see figure 3a).
`
`Reed-Solomon RS (204,188, t = 8) shortened code (see note 1), derived from the original systematic RS (255,239, t = 8)
`code, shall be applied to each randomized transport packet (188 byte) of figure 3b to generate an error protected packet
`(see figure 3c). Reed-Solomon coding shall also be applied to the packet sync byte, either non-inverted (i.e. 47HEX) or
`inverted (i.e. B8HEX).
`
`NOTE 1: The Reed-Solomon code has length 204 bytes, dimension 188 bytes and allows to correct up to 8 random
`erroneous bytes in a received word of 204 bytes.
`
`Code Generator Polynomial: g(x) = (x+λ0)(x+λ1)(x+λ2)...(x+λ15), where λ = 02HEX
`
`Field Generator Polynomial: p(x) = x8 + x4 + x3 + x2 + 1
`
`The shortened Reed-Solomon code may be implemented by adding 51 bytes, all set to zero, before the information bytes
`at the input of an RS (255,239, t = 8) encoder. After the RS coding procedure these null bytes shall be discarded, leading
`to a RS code word of N = 204 bytes.
`
`Following the conceptual scheme of figure 4, convolutional byte-wise interleaving with depth I = 12 shall be applied to
`the error protected packets (see figure 3c). This results in the interleaved data structure (see figure 3d).
`
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`

`12
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`ETSI EN 300 744 V1.2.1 (1999-07)
`
`The convolutional interleaving process shall be based on the Forney approach which is compatible with the Ramsey type
`III approach, with I = 12. The interleaved data bytes shall be composed of error protected packets and shall be delimited
`by inverted or non-inverted MPEG-2 sync bytes (preserving the periodicity of 204 bytes).
`
`The interleaver may be composed of I = 12 branches, cyclically connected to the input byte-stream by the input switch.
`Each branch j shall be a First-In, First-Out (FIFO) shift register, with depth j × M cells where M = 17 = N/I, N = 204.
`The cells of the FIFO shall contain 1 byte, and the input and output switches shall be synchronized.
`
`For synchronization purposes, the SYNC bytes and the SYNC bytes shall always be routed in the branch "0" of the
`interleaver (corresponding to a null delay).
`
`NOTE 2: The deinterleaver is similar in principle, to the interleaver, but the branch indices are reversed
`(i.e. j = 0 corresponds to the largest delay). The deinterleaver synchronization can be carried out by
`routeing the first recognized sync (SYNC or SYNC) byte in the "0" branch.
`
`Figure 3: Steps in the process of adaptation, energy dispersal, outer coding and interleaving
`
`SYNC1 is the non randomized complemented sync byte and SYNCn is the non randomized sync byte, n = 2, 3, ..., 8
`
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`

`13
`
`ETSI EN 300 744 V1.2.1 (1999-07)
`
`Figure 4: Conceptual diagram of the outer interleaver and deinterleaver
`
`4.3.3
`
`Inner coding
`
`The system shall allow for a range of punctured convolutional codes, based on a mother convolutional code of
`rate 1/2 with 64 states. This will allow selection of the most appropriate level of error correction for a given service or
`data rate in either non-hierarchical or hierarchical transmission mode. The generator polynomials of the mother code are
`G1 = 171OCT for X output and G2 = 133OCT for Y output (see figure 5).
`
`If two level hierarchical transmission is used, each of the two parallel channel encoders can have its own code rate.
`In addition to the mother code of rate 1/2 the system shall allow punctured rates of 2/3, 3/4, 5/6 and 7/8.
`
`The punctured convolutional code shall be used as given in table 3. See also figure 5. In this table X and Y refer to the
`two outputs of the convolutional encoder.
`
`Table 2: Puncturing pattern and transmitted sequence after parallel-to-serial conversion for the
`possible code rates
`
`Code Rates r
`
`Puncturing pattern
`
`Transmitted sequence
`(after parallel-to-serial conversion)
`
`1/2
`
`2/3
`
`3/4
`
`5/6
`
`7/8
`
`X: 1
`Y: 1
`X: 1 0
`Y: 1 1
`X: 1 0 1
`Y: 1 1 0
`X: 1 0 1 0 1
`Y: 1 1 0 1 0
`X: 1 0 0 0 1 0 1
`Y: 1 1 1 1 0 1 0
`
`X 1Y1
`
`X1 Y1 Y2
`
`X1 Y1 Y2 X3
`
`X1 Y1 Y2 X3 Y4 X5
`
`X1 Y1 Y2 Y3 Y4 X5 Y6 X7
`
`X1 is sent first. At the start of a super-frame the MSB of SYNC or SYNC shall lie at the point labelled "data input" in
`figure 5. The super-frame is defined in subclause 4.4.
`
`The first convolutionally encoded bit of a symbol always corresponds to X1.
`
`ETSI
`
`13
`
`

`

`14
`
`ETSI EN 300 744 V1.2.1 (1999-07)
`
`Figure 5: The mother convolutional code of rate 1/2
`
`Figure 6: Inner coding and interleaving
`
`4.3.4
`
`Inner interleaving
`
`The inner interleaving consists of bit-wise interleaving followed by symbol interleaving. Both the bit-wise interleaving
`and the symbol interleaving processes are block-based.
`
`4.3.4.1
`
`Bit-wise interleaving
`
`The input, which consists of up to two bit streams, is demultiplexed into v sub-streams, where v = 2 for QPSK, v = 4 for
`16-QAM, and v = 6 for 64-QAM. In non-hierarchical mode, the single input stream is demultiplexed into v sub-streams.
`In hierarchical mode the high priority stream is demultiplexed into two sub-streams and the low priority stream is
`demultiplexed into v-2 sub-streams. This applies in both uniform and non-uniform QAM modes. See figures 7a and 7b.
`
`The demultiplexing is defined as a mapping of the input bits, xdi onto the output bits be,do.
`
`In non-hierarchical mode:
`
`xdi = b[di(mod)v](div)(v/2)+2[di(mod)(v/2)],di(div)v
`
`In hierarchical mode:
`
`x'di = bdi(mod)2,di(div)2
`
`x"di = b[di(mod)(v-2)](div)((v-2)/2)+2[di(mod)((v-2)/2)]+2,di(div)(v-2)
`
`ETSI
`
`14
`
`

`

`15
`
`ETSI EN 300 744 V1.2.1 (1999-07)
`
`Where:
`
`xdi
`
`x’di
`
`x"di
`
`is the input to the demultiplexer in non-hierarchical mode;
`
`is the high priority input to the demultiplexer;
`
`is the low priority input, in hierarchical mode;
`
`di
`
`is the input bit number;
`
`be,do
`
`is the output from the demultiplexer;
`
`e
`
`is the demultiplexed bit stream number (0 ≤ e < v);
`
`do
`
`is the bit number of a given stream at the output of the demultiplexer;
`
`mod
`
`is the integer modulo operator;
`
`div
`
`is the integer division operator.
`
`The demultiplexing results in the following mapping:
`
`QPSK:
`
`x0 maps to b0,0
`
`x1 maps to b1,0
`
`16-QAM non-hierarchical transmission:
`
`16-QAM hierarc