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Digital Video Broadcasting An Overview Prof. Dr. Mehmet Şafak Hacettepe University Dept. of Electrical Digital Video Broadcasting An Overview Prof. Dr. Mehmet Şafak Hacettepe University Dept. of Electrical and Electronics Engineering 06800 Beytepe, Ankara, Turkey [email protected] edu. tr 1

Digital TV How come a man can be so sensitive as to distinguish between Digital TV How come a man can be so sensitive as to distinguish between resolutions 1024 x 678 and 1365 x 768, but can not see the difference between 15 totally different woman shoes ? 14 July 2006 DVB - An Overview I could see the difference if they were on the TV 2

Outline • • • Vision Data Broadcasting Integrated Receiver Decoders (IRD) Transmission on Cable, Outline • • • Vision Data Broadcasting Integrated Receiver Decoders (IRD) Transmission on Cable, Satellite and Terrestrially Interaction Channels The Multimedia Home Platform (MHP) DVB-Handheld Hybrid Networks Prospects for Future. An Overview 14 July 2006 DVB - Developments 3

Vision • Initially, DVB concentrated on broadcasting of audio and video services. • In Vision • Initially, DVB concentrated on broadcasting of audio and video services. • In later phases, DVB addressed areas which lie outside of the classical broadcast world. • Vision defined in 2000: – DVB’s vision is to build a content environment that combines the stability and 14 July 2006 interoperability. DVB - the world of broadcast 4 of An Overview

Data Broadcasting 5 Data Broadcasting 5

Data Broadcasting • A 4: 2: 2 picture requires a raw transmission rate of Data Broadcasting • A 4: 2: 2 picture requires a raw transmission rate of 13. 5 Msamples/s x 16 bits/sample =216 Mbps. • The 216 Mbps just to transmit one digital TV channel is very high, so the need for compression is obvious. • Using compression techniques, the data rates on the order of 3. 2 Mbps per TV channel are currently used. 14 July 2006 DVB - An Overview 6

Data Broadcasting • nn 14 July 2006 DVB - An Overview 7 Data Broadcasting • nn 14 July 2006 DVB - An Overview 7

Data Broadcasting • For real-time HDTV encoders, the rate of improvement in practice has Data Broadcasting • For real-time HDTV encoders, the rate of improvement in practice has been significantly less than for SDTV: – smaller number of channels per multiplex means that the introduction of statistical multiplexing techniques did not yield as much of a benefit for HDTV as it did for SDTV. – Today’s real-time HDTV encoders for H. 264/AVC or VC-1 do not yet fully exercise all of the additional tools in the new algorithms, such as variable block sizes • Within a year, 8 -10 Mbps is expected to be 14 July 2006 DVB - An Overview sufficient for the transmission of HDTV 8

Data Broadcasting Components inside the DVB data container U. Reimers, DVB-the family of international Data Broadcasting Components inside the DVB data container U. Reimers, DVB-the family of international standards for DVB, Proc. IEEE, vol. 94, no. 1, pp. 173 -181, Jan. 2006 14 July 2006 DVB - An Overview 9

Data Broadcasting • The output of the MPEG-2 multiplexer (transport stream) consists of 188 Data Broadcasting • The output of the MPEG-2 multiplexer (transport stream) consists of 188 -byte packets, where different video, audio and data channels are multiplexed. • Depending on the usable data rate of the broadcast channel, the size of the container varies. • The program specific information (PSI) provides a list of packet ID (PID) values of the corresponding program numbers. • The service information (SI) contains the modulation parameters, translates program 14 July 2006 DVB Overview numbers into service. Annames and electronic 10

Data Broadcasting • Data services can be – program related (e. g. , teletext), Data Broadcasting • Data services can be – program related (e. g. , teletext), or – independent of any other service in the multiplex (e. g. , software download, MHP applications, information services). • DVB data broadcasting offers fast Internet access via satellites. – Users may be connected to the Internet via standard modems and in addition install a satellite receiver card into their PCs for 14 July 2006 DVB - An Overview 11 broadband downstream.

Integrated Receiver Decoders (IRD) 12 Integrated Receiver Decoders (IRD) 12

Integrated Receiver Decoders (IRD) • SDTV or HDTV • Baseline IRD or IRD with Integrated Receiver Decoders (IRD) • SDTV or HDTV • Baseline IRD or IRD with digital interface – whether or not they are intended for use with a digital bitstream storage device such as a digital VCR • Video coding formats: – MPEG-2 video or MPEG-4 AVC (H. 264) • Audio coding formats: – Dolby AC-3, DTS- An Overview DVB and MPEG-4 AVC 14 July 2006 13

Integrated Receiver Decoders (IRD) • Reception of DVB services delivered over IP-based networks • Integrated Receiver Decoders (IRD) • Reception of DVB services delivered over IP-based networks • DVB-TXT replaces Teletext – which is transported during the period of the vertical blanking interval (VBI) of analog television. • DVB developed a generic means for the delivery of all VBI data, e. g. , – to enable the control of video recorders, – the signaling of wide screen programs. 14 July 2006 DVB - An Overview 14

Integrated Receiver Decoders (IRD) • As part of DVB signals, it is possible – Integrated Receiver Decoders (IRD) • As part of DVB signals, it is possible – to provide a translation of original soundtrack in the form of subtitles – add graphic elements to the transmitted images, e. g. , station logos. • TV-Anytime information in DVB transport streams – help personal digital recorders (PDR) to search, select and acquire the content, the viewer wishes DVB -record. to An Overview 14 July 2006 15

Transmission on Cable, Satellite and Terrestrially 16 Transmission on Cable, Satellite and Terrestrially 16

Transmission Block diagram of the DVB-T encoder (Blue blocks are used in DVB-C and Transmission Block diagram of the DVB-T encoder (Blue blocks are used in DVB-C and DVB-S as well) U. Reimers, Digital Video Broadcasting, IEEE Comm. Mag. , pp. 104 -110, June 1998 14 July 2006 DVB - An Overview 17

Transmission • DVB-S – Published in 1993 – Modulation: QPSK and BPSK – Convolutional Transmission • DVB-S – Published in 1993 – Modulation: QPSK and BPSK – Convolutional codes concatenated with RS codes • DVB-S 2 – Published in 2003 – Modulation: QPSK, 8 -PSK (broadcast applications), 16 -APSK and 32 -APSK (professional applications) – Backward-compatibity with existing DVB-S receivers – Reasonable receiver complexity – Interactivity (i. e. , Internet access) 14 July 2006 DVB - An Overview 18 – Professional services, such as digital satellite news

Transmission • DVB-S 2 – Best transmission performance • LDPC codes concatenated with BCH Transmission • DVB-S 2 – Best transmission performance • LDPC codes concatenated with BCH codes • Variable and adaptive coding and modulation (recovers rain margin) • Approximately 30 % capacity increase compared to DVBS – Maximum flexibility • • framing structure variable and adaptive coding and modulation can operate in any existing satellite transponder accommodates any input stream format (188 -byte MPEG -2 14 July 2006 transport streams -(packets), continuous bit streams, 19 DVB An Overview

Transmission Performance of LDPC codes over AWGN channel 14 July 2006 DVB - An Transmission Performance of LDPC codes over AWGN channel 14 July 2006 DVB - An Overview (N=64800) 20

Transmission M. Eröz et al. , An innovative LDPC code design with near-Shannonlimit performance Transmission M. Eröz et al. , An innovative LDPC code design with near-Shannonlimit performance and simplementation , IEEE Trans. Communicatio ns, vol. 54, no. 1, pp. 13 -17, January 2006. Comparison of DVB-S 2 (LDPC+ BCH) codes to DVB-S (convolutional+ RS) and channel capacity 14 July 2006 DVB - An Overview 21

Transmission • For each code rate, a parity-check matrix is specified by listing adjacent Transmission • For each code rate, a parity-check matrix is specified by listing adjacent check nodes for the first bit node in a group of M=360. • Irregular LDPC codes are used, where degrees of bit nodes are varying. • DVB-S 2 offers more than 30% capacity improvement • DVB-S 2 is, on average, about only 0. 7 -0. 8 d. B away from Shannon limits. 14 July 2006 DVB - An Overview 22

Transmission • DVB-C – Published in 1994 – Modulation: M-QAM with M=16, 32, 64, Transmission • DVB-C – Published in 1994 – Modulation: M-QAM with M=16, 32, 64, 128 or 256. – Only RS coding is used (no convolutional coding). • DVB-H – Published in November 2004 – Enables the reception of digital TV signals by handheld devices – Additional FEC, in-depth interleaving and 23 14 July 2006 DVB - An Overview time slicing

Transmission • DVB-T, published in 1997, uses OFDM transmissions – – OFDM has 2 Transmission • DVB-T, published in 1997, uses OFDM transmissions – – OFDM has 2 K (subcarriers), 4 K and 8 K versions OFDM allows single-frequency network (SFN) operation Modulation: QPSK, 16 -QAM or 64 -QAM. Hierarchical modulation: High and low priority streams are modulated onto a single DVB-T stream for SDTV and HDTV • Reception by roof-top antenna, portable and mobile reception • DVB-T is adopted in large parts of the world with – – built-in front-ends set-top-boxes PCI cards and USB boxes for desk-top PCs PCMCIA modules for lap-top PCs DVB-T reception in cars in driving speeds 14 July 2006 DVB - An Overview 24

SFN Range vs Mobility Tradeoff • OFDM with 2 K: – widest subcarrier spacing, SFN Range vs Mobility Tradeoff • OFDM with 2 K: – widest subcarrier spacing, hence least susceptible against Doppler shifts (suitable for high-mobility applications) – shortest symbol duration, hence provides the minimum range for SFN. • OFDM with 8 K: – narrowest subcarrier spacing, hence most susceptible against Doppler shifts (suitable for low -mobility applications) – longest symbol duration, hence provides the maximum range for SFN. • OFDM with 4 K provides a trade-off between 14 July 2006 DVB - An Overview 2 K and 8 K 25

Hierarchical Modulation • Two separate data streams modulated onto a single DVB-T stream, – Hierarchical Modulation • Two separate data streams modulated onto a single DVB-T stream, – high-priority (HP) (low data rate) stream is embedded within a low-priority (LP) (high data rate) stream • Receivers with good reception conditions can receive both streams • Only HP streams are received in bad channel conditions, e. g. , mobile and portable reception 14 July 2006 DVB - An Overview 26

Hierarchical Modulation An example of a constellatio n diagram for hierarchical modulation HP bit Hierarchical Modulation An example of a constellatio n diagram for hierarchical modulation HP bit strea m (QPS LP bit K) stream (64 QAM) 14 July 2006 DVB - An Overview 27

Hierarchical Modulation • Broadcasters can target two different types of DVB-T receiver with two Hierarchical Modulation • Broadcasters can target two different types of DVB-T receiver with two completely different (LP or HP) services – LP stream is of higher bit rate, but lower robustness than the HP one; • hence, a trade-off between service bit-rate versus signal robustness • A broadcast could choose to deliver HDTV in the LP stream. 14 July 2006 DVB - An Overview 28

Transmission Choice of parameters for non-hierarchical DVB-T transmission U. Ladebusch and C. A. Liss, Transmission Choice of parameters for non-hierarchical DVB-T transmission U. Ladebusch and C. A. Liss, Terrestrial DVB, Proc. IEEE, vol. 94, no. 1, pp. 183193, Jan 2006 14 July 2006 DVB - An Overview 29

Transmission • Useful bit rate (Mbit/s) for all combinations of guard interval, constellation and Transmission • Useful bit rate (Mbit/s) for all combinations of guard interval, constellation and code rate for nonhierarchical systems for 8 MHz channels (irrespective of the transmission modes) 14 July 2006 DVB - An Overview 30

Transmission • For the hierarchical schemes the useful bit rates can be obtained from Transmission • For the hierarchical schemes the useful bit rates can be obtained from the table as follows: – HP stream: figures from QPSK columns; – LP stream, 16 -QAM: figures from QPSK columns; – LP stream, 64 -QAM: figures from 16 -QAM columns. 14 July 2006 DVB - An Overview 31

Transmission Minimum C/N ratio in the transmission channel required for quasi-error-free (QEF) reception for Transmission Minimum C/N ratio in the transmission channel required for quasi-error-free (QEF) reception for DVB-T • QEF reception: BER <10 -11 at the output of the RS decoder 14 July 2006 DVB - An Overview 32

Interaction Channels 33 Interaction Channels 33

Interaction Channels • The data belonging to a certain interactive service is transmitted in Interaction Channels • The data belonging to a certain interactive service is transmitted in the broadcast channel • The interaction channel enables the user to respond in some way (for instance via the standard remote control ) to the interactive service. • The service provider or network operator listens and reacts to that response. 14 July 2006 DVB - An Overview 34

Interaction Channels Generic system reference model used by DVB for interactive services 14 July Interaction Channels Generic system reference model used by DVB for interactive services 14 July 2006 DVB - An Overview 35 U. Reimers, DVB-the family of international standards for DVB, Proc. IEEE, vol. 94, no. 1,

Interaction Channels • The user’s response may take the form of some simple commands, Interaction Channels • The user’s response may take the form of some simple commands, like – voting in a game show, – purchasing goods advertised in a shopping program. • Interactive services may take the form of full Internet access at the receiver. 14 July 2006 DVB - An Overview 36

Interaction Channels • DVB broadcast channels can deliver information at typical rates of – Interaction Channels • DVB broadcast channels can deliver information at typical rates of – 20 Mbps per channel for terrestrial broadcast networks, – 38 Mbps per channel for broadcast networks via satellite and cable. • Capacity of interaction channel may range from a few kbps to up to 10 Mbps in. July 2006 networks. An Overview cable 14 DVB 37

Interaction Channels • Return Channel Terrestrial (RCT): – Multiple access: OFDMA – Coding: Turbo Interaction Channels • Return Channel Terrestrial (RCT): – Multiple access: OFDMA – Coding: Turbo or RS+ convolutional – Several kbps per TV viewer in cells with 65 km radius – Can handle large peaks in traffic – Use any gaps or under-utilised spectrum – Serve portable and mobile devices – Can operate in 6, 7 and 8 MHz channels – Transmit power < 0. 5 W rms – Time interleaving against impulsive interference 14 July 2006 DVB - An Overview 38

Interaction Channels V. Paxal, DVB with return channel via satellite, DVBRCS 200, www. dvb. Interaction Channels V. Paxal, DVB with return channel via satellite, DVBRCS 200, www. dvb. o rg Simplified diagram of a network architecture for DVB return channel satellite systems (RCS) 14 July 2006 DVB - An Overview 39

The Multimedia Home Platform (MHP) 40 The Multimedia Home Platform (MHP) 40

The Multimedia Home Platform • The MHP specification defines an interface between a digital The Multimedia Home Platform • The MHP specification defines an interface between a digital TV and the network to be connected to in order to support interactive services. • It provides features and functions required for the – Enhanced Broadcast, – Interactive Broadcast, – Internet Access. • The right to use the MHP logo is only granted to. July 2006 MHP implementations that pass those 14 DVB - An Overview 41

The Multimedia Home Platform • MHP offers true multimedia services to TV users. • The Multimedia Home Platform • MHP offers true multimedia services to TV users. • MHP provides a technical solution for the user terminal enabling the reception and presentation of applications in an environment that is – independent of specific equipment vendors, – application authors, – broadcast service An Overview 14 July 2006 DVB - providers. 42

The Multimedia Home Platform • Some examples: – Electronic program guides for the channels/services The Multimedia Home Platform • Some examples: – Electronic program guides for the channels/services provided by a broadcaster – Information services (superteletex, news tickers, stock tickers) – Enhancements to TV content (sporting and voting applications and local play-along games) – E-commerce, e-government and other applications relying Overview secure 14 July 2006 DVB - An upon 43

DVB over IP-based Networks 44 DVB over IP-based Networks 44

DVB over IP-based Networks • A typical IPTV service involves the delivery of broadcast DVB over IP-based Networks • A typical IPTV service involves the delivery of broadcast television, radio and similar ondemand services over IP networks, – hence, a bi-directional IP communication. • An open IP infrastructure is used to reach the customers that can not be reached via classical broadcast networks. – Thus, the geographical reach of DVB services can be extended using broad-band IP networks. 14 July 2006 DVB - An Overview 45

DVB over IP-based Networks Basic IPTV architecture www. dvb. org 14 July 2006 DVB DVB over IP-based Networks Basic IPTV architecture www. dvb. org 14 July 2006 DVB - An Overview 46

DVB over IP-based Networks • The work on IPTV can be divided into three DVB over IP-based Networks • The work on IPTV can be divided into three areas: – Set-top boxes and personal video recorders (PVR), – Home networking, – Additions to the Multimedia Home Platforms (MHP). • A specification has been developed that describes the transport of MPEG-2 based DVB services over IP-based networks. 14 July 2006 DVB - An Overview 47 • Creation of a wireless home network segment

DVB-Handheld 48 DVB-Handheld 48

DVB-Handheld • The system takes into account the specific properties of typical DVB-H terminals: DVB-Handheld • The system takes into account the specific properties of typical DVB-H terminals: – – – – Battery-powered User mobility Handover between cells Mobile multipath channels (antenna diversity) High levels of man-made noise Indoor and outdoor operation Flexibility to operate in various transmission bands and channel bandwidths (to operate in various parts of the world) 14 July 2006 DVB - An Overview 49

DVB-Handheld • DVB-H requires some additional features in the link layer of the existing DVB-Handheld • DVB-H requires some additional features in the link layer of the existing DVB-T standard; – Existing receivers for DVB-T are not disturbed by DVB-H signals • The additional elements in the link layer: – Time slicing • to reduce the average power in the receiver front-end significantly (significant power savings in the receiver) 14 July • to enable smooth. An Overview 2006 DVB - and wireless handover when 50

DVB-Handheld 625 ms The capacity of one DVB-T channel is split between three TV DVB-Handheld 625 ms The capacity of one DVB-T channel is split between three TV programs and an additional eight DVB-H services Slice duration: 625 ms Bit rate: 3. 2 Mbps (=2 Mb/625 ms) U. Reimers, DVB-the family of international standards for DVB, Proc. IEEE, vol. 94, no. 1, pp. 173 -181, Jan. 2006 Average bir 51 rate: 14 July 2006 DVB - An Overview

DVB-Handheld – Additional forward error correction (FEC) gives an improvement in • carrier-to-noise (C/N) DVB-Handheld – Additional forward error correction (FEC) gives an improvement in • carrier-to-noise (C/N) performance • Doppler performance in mobile channels • tolerance to impulsive interference – e. g. , ignition noise in cars. – In view of the restricted data rates and small displays of handheld terminals, it is suggested to exchange MPEG-2 video by H. 264/AVC. 14 July 2006 DVB - An Overview 52

DVB-Handheld • The extensions to the physical layer of DVBT: – Bits in transmitter DVB-Handheld • The extensions to the physical layer of DVBT: – Bits in transmitter parameter signaling (TPS) are upgraded to indicate the presence of DVB-H service – A new 4 K OFDM mode adopted for trading off mobility and single-frequency network (SFN) size • All modulation formats (QPSK, 16 QAM and 64 QAM) with nonhierarchical or hierarchical modes can be used – A new way of using the symbol interleaver of DVBT has been defined (to provide tolerance against impulsive noise) DVB - An Overview 14 July 2006 53

DVB-Handheld • DVB-H is intended to use the same broadcasting spectrum, which DVB-T is DVB-Handheld • DVB-H is intended to use the same broadcasting spectrum, which DVB-T is currently using. • DVB-H services can be introduced – in a dedicated DVB-H network • now it is possible to select 4 K mode or in-depth interleavers – by sharing an existing DVB-T multiplex between DVB-H and DVB-T services – by using the high-priority part of the DVB-T 14 July 2006 DVB - An hierarchical modulation. Overview 54

DVB-Handheld • Possible applications for DVB-H: – IP datacasting service to handheld terminals like DVB-Handheld • Possible applications for DVB-H: – IP datacasting service to handheld terminals like mobile phones – Broadcast services for the mobile phone users • frequency allocation for simultaneous operation? • DVB-H is very spectrum-efficient when compared with the traditional TV services: – One 8 -MHz channel can deliver 30 -50 video streaming services to the small screen terminals • 10 times more than SDTV with MPEG-2 • 20 times more than HDTV with AVC 14 July 2006 DVB - An Overview 55

Hybrid Networks 56 Hybrid Networks 56

Hybrid Networks • Hybrid networks exploit the benefits of both DVB and mobile communications Hybrid Networks • Hybrid networks exploit the benefits of both DVB and mobile communications to enhance services provided to the consumer: – Broadcast networks typically involve wide area and high throughput at the expense of high Tx powers. – Mobile communications offer low-power transmitters covering smaller areas (cells) DVB An Overview • Network cost per - user is higher than for a 14 July 2006 57

Hybrid Networks www. dvb. org 14 July 2006 DVB - An Overview 58 Hybrid Networks www. dvb. org 14 July 2006 DVB - An Overview 58

Hybrid Networks • The IP datacast, used by DVB for a system under development, Hybrid Networks • The IP datacast, used by DVB for a system under development, integrates DVB-H in a hybrid network structure consisting of – a mobile communications network such as GPRS or UMTS, and – an additional DVB-H downstream. • In the process of being standardized • A paid service 14 July 2006 DVB - An Overview • Possibility of handover 59

Hybrid Networks • Architecture of the IP datacast system U. Reimers, DVBthe family of Hybrid Networks • Architecture of the IP datacast system U. Reimers, DVBthe family of international standards for DVB, Proc. IEEE, vol. 94, no. 1, pp. 173 -181, Jan. 2006 14 July 2006 DVB - An Overview 60

Prospects for Future Developments 61 Prospects for Future Developments 61

Future Developments • Mobile communications, digital broadcasting and Internet are converging. • Current achievements Future Developments • Mobile communications, digital broadcasting and Internet are converging. • Current achievements of DVB: – Broadcast delivery to fixed, portable and mobilr terminals – Interactivity-capability in receivers – Data broadcasting over IP-based networks – Multimedia home platform (MHP) to run software applications on all sorts of terminal devices. • To understand a person’s current location, availability, and preferred method of 14 July 2006 DVB - An moment e. g. , a mobile 62 communication at that. Overview

Future Developments • The focus is now moving to the content itself: – The Future Developments • The focus is now moving to the content itself: – The ubiquitous access to media content requires • content management, and • copy protection measures – Portable content formats • To deliver or update the content over fixed and mobile IP networks (for portable video players) DVB - An Overview – TV anytime/anywhere 14 July 2006 63

References • Special issue of Proc. IEEE on global digital television, vol. 94, number References • Special issue of Proc. IEEE on global digital television, vol. 94, number 1, January 2006. • DVB-T: ETSI EN 300 744 V 1. 5. 1 (2004 -11) • DVB-S 2: Draft ETSI EN 302 307 V 1. 1. 1 (2004 -06) • DVB-S: EN 300 421 V 1. 1. 2 (1997 -08) • http: //www. dvb. org 14 July 2006 DVB - An Overview 64

Thanks 65 Thanks 65