SIST ETS 300 744 E1:2005

SLOVENSKI STANDARD
01-november-2005
Digitalna videoradiodifuzija (DVB) – Struktura okvirov, kodiranje kanalov in
modulacija za digitalno prizemno televizijo (DVB-T)
Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for
digital terrestrial television
Ta slovenski standard je istoveten z: ETS 300 744 Edition 1
ICS:
33.170 Televizijska in radijska Television and radio
difuzija broadcasting
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN ETS 300 744
TELECOMMUNICATION March 1997
STANDARD
Source: EBU/CENELEC/ETSI JTC Reference: DE/JTC-DVB-8
ICS: 33.060.20
Key words: DVB, digital, video, broadcasting, terrestrial, MPEG, TV, audio, data
European Broadcasting Union Union Européenne de Radio-Télévision
Digital Video Broadcasting (DVB);
Framing structure, channel coding and modulation for
digital Terrestrial television (DVB-T)
ETSI
European Telecommunications Standards Institute
ETSI Secretariat
Postal address: F-06921 Sophia Antipolis CEDEX - FRANCE
Office address: 650 Route des Lucioles - Sophia Antipolis - Valbonne - FRANCE
X.400: c=fr, a=atlas, p=etsi, s=secretariat - Internet: secretariat@etsi.fr
Tel.: +33 4 92 94 42 00 - Fax: +33 4 93 65 47 16
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 1997.
© European Broadcasting Union 1997.
All rights reserved.
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ETS 300 744: March 1997
Whilst every care has been taken in the preparation and publication of this document, errors in content,
typographical or otherwise, may occur. If you have comments concerning its accuracy, please write to
"ETSI Editing and Committee Support Dept." at the address shown on the title page.

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ETS 300 744: March 1997
Contents
Foreword .5
1 Scope .7
2 Normative references.7
3 Symbols, abbreviations and definition.7
3.1 Symbols .7
3.2 Abbreviations .8
3.3 Definition.9
4 Baseline system .10
4.1 General considerations.10
4.2 Interfacing .11
4.3 Channel coding and modulation .11
4.3.1 Transport multiplex adaptation and randomization for energy dispersal.11
4.3.2 Outer coding and outer interleaving .12
4.3.3 Inner coding.14
4.3.4 Inner interleaving.15
4.3.4.1 Bit-wise interleaving.15
4.3.4.2 Symbol interleaver .19
4.3.5 Signal constellations and mapping.21
4.4 OFDM frame structure.25
4.5 Reference signals .27
4.5.1 Functions and derivation .27
4.5.2 Definition of reference sequence .27
4.5.3 Location of scattered pilot cells .28
4.5.4 Location of continual pilot carriers.28
4.5.5 Amplitudes of all reference information.29
4.6 Transmission Parameter Signalling (TPS) .29
4.6.1 Scope of the TPS .30
4.6.2 TPS transmission format.31
4.6.2.1 Initialization .31
4.6.2.2 Synchronization .31
4.6.2.3 TPS length indicator .32
4.6.2.4 Frame number.32
4.6.2.5 Constellation.32
4.6.2.6 Hierarchy information.32
4.6.2.7 Code rates .33
4.6.2.8 Guard Intervals .33
4.6.2.9 Transmission mode .33
4.6.2.10 Error protection of TPS.33
4.6.3 TPS modulation.34
4.7 Number of RS-packets per OFDM super-frame.34
4.8 Spectrum characteristics and spectrum mask.35
4.8.1 Spectrum characteristics.35
4.8.2 Out-of-band spectrum mask .36
4.8.3 Centre frequency of RF signal.39
Annex A (normative): Simulated system performance.40
Annex B (informative): Definition of P and F .43
1 1
Annex C (informative): Interleaving example .45
Annex D (informative): Guidelines to implementation of the emitted signal.46

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D.1 Use of the Fast Fourier Transform . 46
D.2 Choice of "baseband" centre frequency . 46
D.3 Other potential difficulties . 47
History. 48

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Foreword
This European Telecommunication Standard (ETS) has been produced by the Joint Technical Committee
(JTC) of the European Broadcasting Union (EBU), Comité Européen de Normalisation ELECtrotechnique
(CENELEC) and the European Telecommunications Standards Institute (ETSI).
NOTE: The JTC was established in 1990 to co-ordinate the drafting of ETSs in the specific
field of broadcasting and related fields. Since 1995 the JTC 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
Case Postale 67
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.
Transposition dates
Date of adoption: 28 February 1997
Date of latest announcement of this ETS (doa): 30 June 1997
Date of latest publication of new National Standard
or endorsement of this ETS (dop/e): 31 December 1997
Date of withdrawal of any conflicting National Standard (dow): 31 December 1997

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1 Scope
This ETS describes a baseline transmission system for digital terrestrial television (TV) broadcasting. The
ETS specifies the channel coding/modulation system intended for digital multi-programme
LDTV / SDTV / EDTV / HDTV terrestrial services.
The scope of the specification 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 Normative references
This ETS incorporates by dated and undated reference, provisions from other publications. These
normative references are cited at the appropriate places in the text and the publications are listed
hereafter. For dated references, subsequent amendments to or revisions of any of these publications
apply to this ETS only when incorporated in it by amendment or revision. For undated references the latest
edition of the publication referred to applies.
[1] ISO/IEC 13 818 Part 1, 2, 3 (November 1994): "Coding of moving pictures and
associated audio".
[2] ETS 300 421: "Digital broadcasting systems for television, sound and data
services; framing structure, channel coding and modulation for 11/12 GHz
satellite services".
[3] ETS 300 429: "Digital broadcasting systems for television, sound and data
services. Framing structure, channel coding and modulation for cable systems".
3 Symbols, abbreviations and definition
3.1 Symbols
For the purposes of this ETS, the following symbols apply:
A(e) Output vector from inner bit interleaver e
a Bit number w of inner bit interleaver output stream e
e,w
α Constellation ratio which determines the QAM constellation for the modulation
for hierarchical transmission
B(e) Input vector to inner bit interleaver e
b Bit number w of inner bit interleaver input steam e
e,w
b output bit number do of demultiplexed bit stream number e of the inner
e,do
interleaver demultiplexer
c Complex cell for frame m in OFDM symbol l at carrier k
m,l,k
C’ Complex modulation for a reference signal at carrier k
k
C’ , Complex modulation for a TPS signal at carrier k in symbol l
l k
C/N Carrier-to-noise ratio
Δ Time duration of the guard interval
d Convolutional code free distance
free
f Centre frequency of the emitted signal
c
G , G Convolutional code generator polynomials
1 2
g(x) Reed-Solomon code generator polynomial
h(x) BCH code generator polynomial
H(q) Inner symbol interleaver permutation

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H (w) Inner bit interleaver permutation
e
i Priority stream index
I Interleaving depth of the outer convolutional interleaver
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
K , K Carrier number of the lower and largest active carrier respectively in the OFDM
min max
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
N Inner symbol interleaver block size
max
p Scattered pilot insertion index
p(x) RS code field generator polynomial
P (f) Power Spectral Density for carrier k
k
P(n) Interleaving pattern of the inner symbol interleaver
r Code rate for priority level i
i
s TPS bit index
i
t Number of bytes which can be corrected by the Reed-Solomon decoder
T Elementary time period
T Duration of an OFDM symbol
S
T Time duration of a frame
F
T Time duration of the useful (orthogonal) part of a symbol, without the guard
U
interval
u Bit numbering index
v Number of bits per modulation symbol
w Value of reference PRBS sequence applicable to carrier k
k
x Input bit number di to the inner interleaver demultiplexer
di
x' High priority input bit number di to the inner interleaver demultiplexer
di
x" Low priority input bit number di to the inner interleaver demultiplexer
di
Y Output vector from inner symbol interleaver
Y' Intermediate vector of inner symbol interleaver
y Bit number q of output from inner symbol interleaver
q
y' Bit number q of intermediate vector of inner symbol interleaver
q
z Complex modulation symbol
3.2 Abbreviations
For the purposes of this ETS, the following abbreviations apply:
ACI Adjacent Channel Interference
AFC Automatic Frequency Control
BCH Bose - Chaudhuri - Hocquenghem code
BER Bit Error Ratio
D/A Digital-to-Analogue converter
DBPSK Differential Binary Phase Shift Keying
DFT Discrete Fourier Transform
DVB Digital Video Broadcasting
DVB-T DVB-Terrestrial
EDTV Enhanced Definition Television
ETS European Telecommunication Standard
FEC Forward Error Correction
FFT Fast Fourier Transform
FIFO First-In, First-Out shift register
HDTV High Definition Television
HEX Hexadecimal notation
HP High Priority bit stream
IF Intermediate Frequency
IFFT Inverse Fast Fourier Transform

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LDTV Limited Definition Television
LO Local Oscillator
LP Low Priority bit stream
LSB Least Significant Bit
MPEG Moving Picture Experts Group
MSB Most Significant Bit
MUX Multiplex
NICAM Near-Instantaneous companded Audio Multiplex
OCT Octal notation
OFDM Orthogonal Frequency Division Multiplexing
PAL Phase Alternating Line
PCR Program Clock Reference
PID Program Identifier
PRBS Pseudo-Random Binary Sequence
QAM Quadrature Amplitude Modulation
QEF Quasi Error Free
QPSK Quaternary Phase Shift Keying
RF Radio Frequency
RS Reed-Solomon
SDTV Standard Definition Television
SECAM Système Sequentiel Couleur A Mémoire
SFN Single Frequency Network
TPS Transmission Parameter Signalling
TV Television
UHF Ultra-High Frequency
VHF Very-High Frequency
3.3 Definition
For the purposes of this ETS, the following definition applies:
constraint length: Number of delay elements +1 in the convolutional coder.

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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):
- 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;
- OFDM transmission.
The system is directly compatible with MPEG-2 coded TV signals ISO/IEC 13 818 [1].
Since the system is being designed for digital terrestrial television services to operate within the existing
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 services. It is also a requirement that the System
allows the maximum spectrum efficiency when used within the UHF bands; this requirement can be
achieved by utilizing Single Frequency Network (SFN) operation.
NOTE: I.e. 8 MHz channel spacing. An adaptation of this specification for 7 MHz channels can
be achieved by scaling down all system parameters according to a change of the system
clock rate from 64/7 MHz to exactly 8,0 MHz. The frame structure and the rules for
coding, mapping and interleaving are kept, only the data capacity of the system is
reduced by a factor 7/8 due to the respective reduction of signal bandwidth.
To achieve these requirements an OFDM system with concatenated error correcting coding is being
specified. To maximize commonality with the Satellite baseline specification (see ETS 300 421 [2]) and
Cable baseline specifications (see ETS 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,

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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 s,
audio interruption for approximately 0,2 s) while the inner decoder and the various source decoders are
suitably reconfigured and reacquire lock.
Figure 1: Functional block diagram of the System
4.2 Interfacing
The Baseline System as defined in this specification is delimited by the following interfaces:
Table 1: Interfaces for the Baseline System
Location Interface Interface type Connection
Transmit Station Input MPEG-2 transport stream(s) multiplex from MPEG-2
multiplexer
Output RF signal to aerial
Receive Installation Input RF from aerial
Output MPEG-2 transport stream multiplex 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. 47 ). The processing order at the transmitting side shall
HEX
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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Figure 2: Scrambler/Descrambler schematic diagram
The polynomial for the pseudo random binary sequence (PRBS) generator shall be (see note):
14 15
1 + X + X
NOTE: The polynomial description given here is in the form taken from the Satellite baseline
specification ETS 300 421 [2]. Elsewhere, in both the Satellite baseline specification
and in this specification, 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
47 (SYNC) to B8 (SYNC). This process is referred to as "transport multiplex adaptation" (see
HEX HEX
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. B8 ). To aid other synchronization functions, during the
HEX
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), 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. 47 ) or inverted (i.e. B8 ).
HEX HEX
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.
0 1 2 15
Code Generator Polynomial: g(x) = (x+λ )(x+λ )(x+λ ).(x+λ ), where λ = 02
HEX
8 4 3 2
Field Generator Polynomial: p(x) = x + x + x + x + 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.

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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).
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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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 ½ 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 G = 171 for X output and G = 133 for Y output (see figure 5).
1 OCT 2 OCT
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 ½ 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 below. 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 X: 1 X Y
1 1
Y: 1
2/3 X: 1 0 X Y Y
1 1 2
Y: 1 1
3/4 X: 1 0 1 X Y Y X
1 1 2 3
Y: 1 1 0
5/6 X: 1 0 1 0 1 X Y Y X Y X
1 1 2 3 4 5
Y: 1 1 0 1 0
7/8 X: 1 0 0 0 1 0 1 X Y Y Y Y X Y X
1 1 2 3 4 5 6 7
Y: 1 1 1 1 0 1 0
X 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 X .
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Figure 5: The mother convolutional code of rate ½
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, x onto the output bits b .
di e,do
In non-hierarchical mode:
x = b
di>di(mod)v@(div)(v/2)+2>di(mod)(v/2)@,di(div)v
In hierarchical mode:
x' = b
di di(mod)2,di(div)2
x" = b
di>di(mod)(v-2)@(div)((v-2)/2)+2>di(mod)((v-2)/2)@+2,di(div)(v-2)

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Where: x is the input to the demultiplexer in non-hierarchical mode;
di
x' is the high priority input to the demultiplexer;
di
x" is the low priority input, in hierarchical mode;
di
di is the input bit number;
b is the output from the demultiplexer;
e,do
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: x maps to b
0 0,0
x maps to b
1 1,0
16-QAM non-hierarchical transmission: 16-QAM hierarchical transmission:
x maps to b x' maps to b
0 0,0 0 0,0
x maps to b x' maps to b
1 2,0 1 1,0
x maps to b x" maps to b
2 1,0 0 2,0
x maps to b x" maps to b
3 3,0 1 3,0
64-QAM non-hierarchical transmission: 64-QAM hierarchical transmission:
x maps to b x' maps to b
0 0,0 0 0,0
x maps to b x' maps to b
1 2,0 1 1,0
x maps to b x" maps to b
2 4,0 0 2,0
x maps to b x" maps to b
3 1,0 1 4,0
x maps to b x" maps to b
4 3,0 2 3,0
x maps to b x" maps to b
5 5,0 3 5,0
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Figure 7a: Mapping of input bits onto output modulation symbols, for non-hierarchical
transmission modes
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Figure 7b: Mapping of input bits onto output modulation symbols, for hierarchical transmission
modes
Each sub-stream from the demultiplexer is processed by a separate bit interleaver. There are therefore up
to six interleavers depending on v, labelled I0 to I5. I0 and I1 are used for QPSK, I0 to I3 for 16-QAM and
I0 to I5 for 64-QAM.
Bit interleaving is performed only on the useful data. The block size is the same for each interleaver, but
the interleaving sequence is different in each case. The bit interleaving block size is 126 bits. The block
interleaving process is therefore repeated exactly twelve times per OFDM symbol of useful data in the 2k
mode and forty-eight times per symbol in the 8k mode.
For each bit interleaver, the input bit vector is defined by:
B(e) = (b , b , b , ., b ) where e ranges from 0 to v-1
e,0 e,1 e,2 e,125
The interleaved output vector A(e) = (a , a , a , ., a ) is defined by:
e,0 e,1 e,2 e,125
a = b w = 0, 1, 2, ., 125
e,w e,He(w)
where H (w) is a permutation function which is different for each interleaver.
e
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H (w) is defined as follows for each interleaver:
e
I0: H (w) = w
I1: H (w) = (w + 63) mod 126
I2: H (w) = (w + 105) mod 126
I3: H (w) = (w + 42) mod 126
I4: H (w) = (w + 21) mod 126
I5: H (w) = (w + 84) mod 126
The outputs of the v bit interleavers are grouped to form the digital data symbols, such that each symbol
of v bits will consist of exactly one bit from each of the v interleavers. Hence, the output from the bit-wise
interleaver is a v bit word y' that has the output of I0 as its most significant bit, i.e.:
y' = (a , a , ., a )
w 0,w 1,w v-1,w
4.3.4.2 Symbol interleaver
The purpose of the symbol interleaver is to map v bit words onto the 1 512 (2k mode) or 6 048 (8k mode)
active carriers per OFDM symbol. The symbol interleaver acts on blocks of 1 512 (2k mode) or 6 048
(8k mode) data symbols.
Thus in the 2k mode, 12 groups of 126 data words from the bit interleaver are read sequentially into a
vector Y' = (y' , y' , y' ,.y' ). Similarly in the 8k mode, a vector Y' = (y' , y' , y' ,.y' ) is assembled
0 1 2 1511 0 1 2 6047
from 48 groups of 126 data words.
The interleaved vector Y = (y , y , y ,.y ) is defined by:
0 1 2 Nmax-1
y y' for even symbols for q = 0,.,N -1
H(q) = q max
y = y' for odd symbols for q = 0,.,N -1
q H(q) max
where N = 1 512 in the 2k mode and N = 6 048 in the 8k mode.
max max
The symbol index, defining the position of the current OFDM symbol in the OFDM frame, is defined in
subclause 4.4.
H(q) is a permutation function defined by the following.
An (N - 1) bit binary word R' is defined, with N log M , where M 2 048 in the 2k mode and
r i r = 2 max max =
M = 8 192 in the 8k mode, where R' takes the following values:
max i
i = 0,1: R' [N -2, N -3,.,1,0] = 0,0,.,0,0
i r r
i = 2: R' [N -2, N -3,.,1,0] = 0,0,.,0,1
i r r
2
max i r r i-1 r r
in the 2k mode: R' [9] = R' [0] ⊕ R' [3]
i i-1 i-1
in the 8k mode: R' [11] = R' [0] ⊕ R' [1] ⊕ R' [4] ⊕ R' [6]  }
i i-1 i-1 i-1 i-1
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ETS 300 744: March 1997
A vector R is derived from the vector R' by the bit permutations given in tables 3a and 3b.
i i
Table 3a: Bit permutations for the 2k mode
R' bit positions 9 8 7 6 5 4 3 2 1 0
i
R bit positions 0 7 5 1 8 2 6 9 3 4
i
Table 3b: Bit permutations for the 8k mode
R' bit positions 11 10 9 8 7 6 5 4 3 2 1 0
i
R bit positions 5 11 3 0 10 8 6 9 2 4 1 7
i
The permutation function H(q) is defined by the following algorithm:
q = 0;
for (i = 0; i < M ; i = i + 1)
max
N2−
r
N1− j
r
{ H(q)=⋅(i mod2) 2+ R (j)⋅ 2;
i
∑
j0=
if (H(q) max
A schematic block diagram of the algorithm used to generate the permutation function is represented in
figure 8a for the 2k mode and in figure 8b for the 8k mode.
toggle
R'
T
9 8 7 6 5 4 3 2 1 0
Control
wires permutation
Unit R
MSB
skip address
check
H(q)
Figure 8a: Symbol interleaver address generation scheme for the 2k mode

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ETS 300 744: March 1997
toggle
T
R'
11 10 9 8 7 6 5 4 3 2 1 0
Control
wires permutation
Unit R
MSB
skip address
check
H(q)
Figure 8b: Symbol interleaver address generation scheme for the 8K mode
In a similar way to y', y is made up of v bits:
y = (y , y ,., y )
q' 0,q' 1,q' v-1,q'
where q' is the symbol number at the output of the symbol interleaver.
These values of y are used to map the data into the signal constellation, as described in subclause 4.3.5.
4.3.5 Signal constellations and mapping
The system uses Orthogonal Frequency Division Multiplex (OFDM) transmission. All data carriers in one
OFDM frame are either QPSK, 16-QAM, 64-QAM, non-uniform-16-QAM or non-uniform-64-QAM using
Gray mapping.
Gray mapping is applied according to the following method for QPSK, 16-QAM and 64-QAM. The
mapping shall be performed according to figure 9.

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ETS 300 744: March 1997
Figure 9a: The QPSK, 16-QAM and 64-QAM mappings and the corresponding bit patterns
(non-hierarchical, and hierarchical with α = 1)
The y denote the bits representing a complex modulation symbol z.
u,q'
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ETS 300 744: March 1997
Figure 9b: Non-uniform 16-QAM and 64-QAM mappings with α = 2
The y denote the bits representing a complex modulation symbol z.
u,q'
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ETS 300 744: March 1997
Figure 9c: Non-uniform 16-QAM and 64-QAM mappings with α = 4
The y denote the bits representing a complex modulation symbol z.
u,q'
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ETS 300 744: March 1997
Non-hierarchical transmission:
The data stream at the output of the inner interleaver consists of v bit words. These are mapped onto a
complex number z, according to figure 9a.
Hierarchical transmission:
In the case of hierarchical transmission, the data streams are formatted as shown in figure 7b, and then
the mappings as shown in figures 9a, 9b, or 9c are applied, as appropriate.
For hierarchical 16 QAM:
The high priority bits are the y and y bits of the inner interleaver output words. The low priority bits
0,q' 1,q'
are the y and y bits of the inner interleaver output words. The mappings of figures 9a, 9b or 9c are
2,q' 3,q'
applied, as appropriate. For example, the top left constellation point, corresponding to 1 000 represents
y =1, y = y = y = 0. If this constellation is decoded as if it were QPSK, the high priority bits, y ,
0,q' 1,q' 2,q' 3,q' 0,q'
y will be deduced. To decode the low priority bits, the full constellation shall be examined and the
1,q'
appropriate bits (y , y ) extracted from y , y , y , y
2,q' 3,q' 0,q' 1,q' 2,q' 3,q'.
For hierarchical 64 QAM:
The high priority bits are the y and y bits of the inner interleaver output words. The low priority bits
0,q' 1,q'
are the y , y , y and y bits of the inner interleaver output words. The mappings of figures 9a, 9b
2,q' 3,q' 4,q' 5,q'
or 9c are applied, as appropriate. If this constellation is decoded as if it were QPSK, the high priority bits,
y , y will be deduced. To decode the low priority bits, the full constellation shall be examined and the
0,q' 1,q'
appropriate bits (y , y , y , y ,) extracted from y , y , y , y , y , y
2,q' 3,q' 4,q' 5,q' 0,q' 1,q' 2,q' 3,q' 4,q' 5,q'.
4.4 OFDM frame structure
The transmitted signal is organized in frames. Each frame has a duration of T , and consists of 68 OFDM
F
symbols. Four frames constitute one super-frame. Each symbol is constituted by a set of K = 6 817
carriers in the 8k mode and K = 1 705 carriers in the 2k mode and transmitted with a duration T . It is
S
composed by parts: a useful part with duration T and a guard interval with a duration Δ. The guard
U
interval consists in a cyclic continuation of the useful part, T , and is inserted before it. Four values of
U
guard intervals may be used according to table 5 where the different values are given both in multiples of
the elementary period T = 7/64 μs and in microseconds.
The symbols in an OFDM frame are numbered from 0 to 67. All symbols contain data and reference
information.
Since the OFDM signal comprises many separately-modulated carriers, each symbol can in turn be
considered to be divided into cells, each corresponding to the modulation carried on one carrier during
one symbol.
In addition to the transmitted data an OFDM frame contains:
- Scattered pilot cells;
- Continual pilot carriers;
- TPS carriers.
The pilots can be used for frame synchronization, frequency synchronization, time synchronization,
channel estimation, transmission mode identification and can also be used to follow the phase noise.
The carriers are indexed by k ∈ [K ; K ] and determined by K = 0 and K = 1 704 in 2k mode
min max min max
and 6 816 in 8k mode respectively. The spacing between adjacent carriers is 1/T while the spacing
U
between carriers K and K are determined by (K-1)/T . The numerical values for the OFDM
min max U
parameters for the 8k and 2k modes are given in table 4.

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ETS 300 744: March 1997
Table 4: Numerical values for the OFDM parameters for the 8k and 2k mode
Parameter 8k mode 2k mode
Number of carriers K 6 817 1 705
Value of carrier number K 00
min
Value of carrier number K 6 816 1 704
max
Duration T
896 μs 224 μs
U
Carrier spacing 1/T (note 1) 1 116 Hz 4 464 Hz
U
Spacing between carriers K and K (K-1)/T 7,61 MHz 7,61 MHz
min max U
(note 2)
NOTE 1: Values in italics are approximate values.
NOTE 2: 6,66 MHz in the case of 7 MHz wide channels.
The emitted signal is described by the following expression:
K
∞ 67
max
 
jf⋅⋅2π ⋅t
c
st()=⋅Re e c⋅ ψ ()t
 
∑∑∑
ml,,k m,l,k
 
m=0l=0kK=
 min 
k'
jt⋅⋅26π ⋅()−Δ−l⋅T−8⋅m⋅T
ss
 T
U
 ()lm+⋅68 ⋅T≤t≤(lm+ 68⋅ + 1)⋅T
e
ss
where ψ ()t =

ml,,k
else


where:
k denotes the carrier number;
l denotes the OFDM symbol number;
m denotes the transmission frame number;
K is the number of transmitted carriers;
T is the symbol duration;
S
T is the inverse of the carrier spacing;
U
Δ is the duration of the guard interval;
f is the central frequency of the RF signal;
c
k' is the carrier index relative to the centre frequency, k' = k - (K + K ) / 2;
max min
c complex symbol for carrier k of the Data symbol no. 1 in frame number m;
m,0,k
c complex symbol for carrier k of the Data symbol no. 2 in frame number m;
m,1,k
...
c complex symbol for carrier k of the Data symbol no. 68 in frame number m.
m,67,k
Table 5: Duration of symbol part for the allowed guard intervals
Mode 8k mode 2k mode
¼ 1/8 1/16 1/32 ¼ 1/8 1/16 1/32
Guard interval
Δ / / T
U
Duration of 8 192 × T 2 048 × T
symbol part T 896 μs 224 μs
U
Duration of guard 2 048 × T 1 024 × T 512 × T 256 × T 512 × T 256 × T 128 × T 64 × T
interval Δ 224 μs 112 μs 56 μs 28 μs 56 μs 28 μs 14 μs 7 μs
Symbol duration 10 240 × T 9 216 × T 8 704 × T 8 448 × T 2 560 × T 2 304 × T 2 176 × T 2 112 × T
T = Δ + T 1 120 μs 1 008 μs 952 μs 924 μs 280 μs 252 μs 238 μs 231 μs
S U
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ETS 300 744: March 1997
The c values are normalized modulation values of the constellation point z (see figure 9) according to
m,l,k
the modulation alphabet used for the data. The normalization factors yield E[c⋅c*] = 1 and are shown in
table 6.
Table 6: Normalisation factors for data symbols
Modulation scheme Normalisation factor
QPSK c = z/√2
16-QAM
α = 1 c = z/√10
α = 2 c = z/√20
α = 4 c = z/√52
64-QAM
α = 1 c = z/√42
α = 2 c = z/√60
α = 4 c = z/√108
4.5 Reference signals
4.5.1 Functions and derivation
Various cells within the OFDM frame are modulated with reference information whose transmitted value is
known to the receiver. Cells containing reference information are transmitted at "boosted" power level
(see subclause 4.5.5). The information transmitted in these cells are scattered or continual pilot cells.
Each continual pilot coincides with a scattered pilot every fourth symbol; the number of useful data carriers
is constant from symbol to symbol: 1 512 useful carriers in 2k mode and 6 048 useful carriers in 8k mode.
The value of the scattered or continual pilot information is derived from a PRBS (Pseudo Random Binary
Sequence) which is a series of values, one for each of the t
...