the digital video broadcast (dvb) project
TRANSCRIPT
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Agenda
Introduction to The DVB Forum Standards and Specifications portfolio Comparison with competing standards Evolution System Architecture Protocol stack How is HSC involved?
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The DVB Forum
The European Launching Group (PPP) The DVB Forum incorporated in 9/93
Managed by the DVB Project Office of the European Broadcasting Union (EBU), Geneva
Members develop and mutually agree on specifications
Specifications approved by EBU
WG on DTV ~ 300 members (2007)
Open to all organizations
involved in broadcasting technologies
/CENELEC/ETSI/ITU-T/ITU-R; become standards
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The DVB Forum
Timeline of DVB ’91 – ELG (PPP) 9/93 – DVB incorporated with 80 members 11/93 – MPEG2 (ISO/IEC 13818-2) approved by ISO 5/94 – DVB-CSA approved 9/94 – DVB-CA approved 11/94 – ITU comes aboard
3/95 – DVB-CI approved 12/95 – DVB-T approved
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The DVB Forum
Timeline of DVB 4/96 – DVB-T begins trials in the UK ‘96 – DVB-S approved ‘96 – DVB-C approved 4/97 – HDTV compatibility 4/97 – DVB-SIM (Simulcrypt) approved 4/97 – DVB-IPDC approved 4/13/99 – Negotiations with China
7/19/99 – India adopts DVB-T CMMB?
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The DVB Forum
Timeline of DVB 9/99 – Mobile TV demonstrated in trams in
Amsterdam, The Netherlands 4/10/00 – Hierarchical Modulation for simulcast of
HDTV and SDTV on DVB-T
5/00 – DVB-MHP approved 2/14/01 – DVB-RCS approved 4/7/03 – Work on DVB-GEM begins 11/04 – DVB-H approved 2/14/07 – DVB-SH approved
NAB
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Specification and Standardization
The hierarchy General Assembly
Steering Board
DVB Project Office (Project Management)
Commercial Module
Technical Module
IPR Module Public Relations/Communications/Promotions Module
WG
WG
DVB Project Office
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Technical Examine technological implications, explore
available technologies WG reaches consensus Support from CM
Steering Board Overall policy direction, sets priority, co-ordination,
budget, regulatory guidelines
Specification and Standardization The hierarchy Approved!!
(EBU/ETSI/CENELEC/ITU-T/ITU-R) General Assembly
Commercial Market research WG draws up user requirements, market
parameters (pricing, functionality)
IPR IPR issues
Communications and Promotions Branding and Communications
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Salient Features of the DVB standards Market led
Priority to commercial requirements Economies of scale Public benefits!!
Interoperable Independent of OEM Maximum commonality with MPEG2 Transport (ISO/IEC
13818-2) Flexible
Supports PAL, NTSC, SECAM SDTV/HDTV MPEG4-10/H.264, MPEG4-2/H.263+
Innovation Universal adoption
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The DVB standards - Evolution DVB-S (1993)
LoS > 10 GHz Simple QPSK modulation
DVB-C (1994) < 10 GHz DVB-CS for broadcasting a complete satellite channel
mux on a cable channel DVB-T
More complex (NLoS, multipath, fading) First COFDM standard (2K and 8K mode; optional 4K mode) QPSK, 16QAM, 64QAM; optional indepth interleaver for
time diversity Hierarchical modulation 5 (optional)/6/7/8 MHz channels
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The DVB standards - Evolution
DVB-S2 2 versions – one is backward compatible with DVB-S,
the other is not!! EU plans to support both 30% more capacity 8PSK, Turbo coding
DVB-H (2004) NLoS 4K mode, 5 MHz BW mode and indepth interleaver
become compulsory features First standard with Time Slicing for power saving DVB-T + 4K COFDM + Time Slicing + MPE-FEC +
Indepth Interleaver + 5 MHz channel
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The DVB standards - Evolution
DVB-SH (2007) Introduced as DVB-SSP Based on DVB-S and DVB-H principles DVB-H – (CC, RS16) + Turbo coding + 1K COFDM +
1.7 MHz channel bandwidth + Flexible temporal interleaving (Extended MPE-FEC)
Direct satellite link (SC) Complementary ground coverage (CGC) – Gap Filler DVB-SH-A (COFDM on SC and CGC) DVB-SH-B (COFDM on CGC, TDM on SC)
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The Competition….
T-DMB: RS (MPEG) + CC(Viterbi) + Service time interleaver + 2K/1K/½K/¼K mode + DQPSK + 1.5 MHz channel bandwidth
ISDB-T: RS (MPEG) + CC(Viterbi) + sub-band time interleaver + outer (bit) interleaver + inner (symbol) interleaver + DQPSK/QPSK/16QAM/64QAM + 6/7/8 MHz
DMB-TH: BCH + LDPC + Time Interleaver + 4K mode + 4QAM/16QAM/32QAM/64QAM + 6/7/8 MHz
MediaFLO: RS + Turbo Coding + Time Interleaver + 4K mode + TDM/FDM pilots + QPSK/16QAM + 5/6/7/8 MHz
What they do….and how they do it?
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…is beaten handsdown!!!
DVB-H: MPE-FEC (RS64 + Virtual time interleaver) + Time slicing + RS16 + CC(Viterbi) + Outer Interleaver + Inner Interleaver + Indepth Interleaver(optional) + QPSK/16QAM/64QAM + 2K/4K/8K mode + 5/6/7/8 MHz DVB-SH: MPE-FEC (RS64 + Virtual time interleaver) + MPE-FEC Extension + Turbo coding + Outer Interleaver + Inner Interleaver + Indepth Interleaver(optional) + QPSK/16QAM/64QAM + 1K/2K/4K/8K mode + 1.7/5/6/7/8 MHz
What they do….and how they do it?
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LLC/MAC – DVB-H
Reed-Solomon (255,191,64) Forward Error Correction (FEC)
Multi Protocol Encapsulation (MPE)
IP Data
IPv4/v6,< 4096 bytes
188 bytes (ISO/IEC 13818-2 compliant)
PHY
Virtual Time Interleaving1 MPE Frame = 1 to 2 Mbits
MPEG2 Transport Stream (TS) slicer
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LLC/MAC- DVB-SHReed-Solomon (255,191,64) Forward Error Correction (FEC)
Multi Protocol Encapsulation (MPE)
IP Data
IPv4/v6,< 4096 bytes
188 bytes (ISO/IEC 13818-2 compliant)
PHY
Virtual Time Interleaving1 MPE Frame = 1 to 2 Mbits
MPEG2 Transport Stream (TS) slicer
Extended MPE
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PHY – DVB-H
Convolutional Coding (Viterbi)
Reed-Solomon (204, 188, 16) FEC
Bit Interleaver
Symbol Interleaver
Symbol Mapper
MPEG2 TS
188 bytes
Scrambler
Still 188 byte packets!!
Energy dispersal; helps in bit sync
204 x n bytes
Coding rate of n
(Digital modulation - QPSK/16QAM/64QAM; 2/4/6 bits per COFDM symbol)
1 symbol
1 symbol
16QAM64QAM
QPSK
RF
204 bytes
HPLP
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PHY – DVB-SH (simplified)
Turbo coder (Convolutional Coder + inbuilt interleaving)
Symbol Mapper
MPEG2 TS
188 bytes
Scrambler
Still 188 byte packets!!
Energy dispersal; helps in bit sync
(Digital modulation - QPSK/16QAM/64QAM; 2/4/6 bits per COFDM symbol)
1 symbol
1 symbol
16QAM64QAM
QPSK
RF
HP LP
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RF Receiver
Symbol FFT
Antenna
IFFT in transmitter
1K, 2K, 4K, 8K sample FFT per OFDM symbol
Complex number
form (analog)
GSM cutoff
D/A
Decision Feedback (Channel State Information (CSI)) from baseband/MAC
Frequency Domain Equalizer (DFE)
FIR filter (simple sample multiplication due to circular convolution/cyclic prefixing) For GSM850 in
UHF Band V
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Power saving in DVB-H and DVB-SH: Time Slicing
1 OFD
M sy
mbo
l (1/
2/4/
8 K
sub-
carri
ers i
n 1.
7/5/
6/7/
8
MHz)
Tg
Tu
Tu is the useful COFDM symbol period, during which detection takes place using FFT Tg is the Guard Interval (GI) to protect against multipath
Pilot carriers
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Single Frequency Network (SFN)
A unique feature of DVB-H/DVB-SH A single frequency allocated for the entire network Huge cost savings in procuring spectrum during auctions Several engineering challenges
SFN networks are more susceptible to multipath and inter-carrier interference
All transmitters of the network transmit…. ….At the same time ….Same date bits ….At the same carrier frequency
Higher GI used to mitigate effects of more severe multipath in SFN networks However, higher GI means lower capacity and smaller
cell size!!!
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Six Degrees of Freedom GI (Tg)
A fraction of the OFDM symbol time period A higher number translates to better multipath tolerance, but also
means lower capacity and smaller SFN size; less cost effective FFT size (mode)
1 (DVB-SH only)/2/4 (optional in DVB-T/available in DVB-H)/8K mode A higher mode translates to higher capacity but lower tolerance to
Doppler (forces high speed vehicles to a higher bandwidth for same capacity)
Channel bandwidth 1.7 MHz (DVB-SH only), 5 MHz (optional in DVB-T/available in DVB-H), 6
MHz, 7 MHz, 8 MHz Modulation scheme
QPSK (4QAM), 16QAM, 64QAM 4QAM - lowest capacity (2 bits/sub-carrier); least susceptible to noise 64QAM - highest capacity (6 bits/sub-carrier); most susceptible to noise
Carrier frequency Lower frequency for faster vehicles, but larger antenna size VHF to S Band (DVB-H), C/Ku/Ka bands (DVB-SH)
Hierarchical Modulation HDTV/SDTV, MPEG2/IP multiplexing
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How is HSC involved?
+ = ?? Opportunities are being explored
Possible leverage in DVB-MHP, DVB-GEM, IPTV Tracking of DVB-SH, DVB-H2, DVB-T2 and DVB-S2
(DVB 2.0) specifications Integration of DVB-H and DVB-SH onto GMR-1 HNS + HSC + Terrastar