DVB-H

1. DVB-H digital video broadcasting for handheld devices Björn Forss Magnus Melin

2. Introduction • Convergence of digital media and communication give users possibility to consume most digital content also in mobile environment • The emerging DVB-H standard aims to provide digital TV reception in mobile devices • Earlier known as DVB-X • DVB-H is being standardized by and ad hoc group of the DVB organization • Expected to be standardized in the first quarter of 2004 • DVB-H combines traditional television broadcast standards with elements specific to handheld devices; mobility, smaller screens and antennas, indoor coverage and reliance on battery power 

3. Motivation for creating DVB-H • Why not use UMTS? • Not scalable for mass content delivery • For delivery of mass media content, broadcast networks should be preferred over point-to-point cellular networks • Why not use DVB-T? • Was designed for rooftop reception • Need for an efficient power saving mechanism • Inadequate impulse noise protection • Why not use DAB? • Designed for devices with similar power constraints but too narrow spectrum is assigned for data transmission DAB = Digital Audio Broadcasting

4. DVB-T • Terrestrial Digital Television Standard • Used in 36 countries world wide • One-to-many broadband wireless data transport • Video, audio, data and – importantly – IP packets • Scalable: cell size up to 100km (DVB-H cell size is smaller) • Huge capacity: 54 channels each 5-32Mbit/s • Shut down of analog TV will free up huge frequency capacity for DVB-T usage DVB-T = Digital Video Broadcasting - Terrestrial

5. DVB-T (2) • Developed for MPEG-2 stream distribution, but can basically carry any data • Flexible, has many modes, 4.98-31.67 Mbit/s @ C/N=25dB • COFDM multicarrier modulation with 2k and 8k modes • One DVB channel is ~8MHz • 1705 sub carriers (spacing: 4464 Hz) - 2k mode • 6817 sub carriers (spacing: 1116 Hz) - 8k mode • Carrier modulation: QPSK, 16 QAM or 64 QAM • Error correction: convolutional code and Salomon-Reed • Basic mode in Finland: • 64 QAM, code rate = 2/3, guard interval 1/8 • Gives 22.12 Mbits/s capacity when C/N=19.2 dB and 8 MHz channel • COFDM = Coded Orthogonal Frequency Division MultiplexingC/N = Carrier to Noise ratio

6. Mobile reception of DVB-T • DVB-T includes hierarchical modes where two transport streams can be sent simultaneously • Low capacity, high capacity • DVB-T can also be used for broadcast to mobile devices, but a suitable mode have to be selected • 8k 64 QAM: < 50 km/h • 2k QPSK: > 400 km/h tolerable • A separate network for DVB-H is desired • Optimization of speed, coverage and capacity

7. 2k, 4k or 8k and why? • A small number of sub-carrier provides (like in 2k): • large inter-carrier spacing -> gives tolerance to the echoes affected by Doppler • short symbol duration ->limits the maximum delay of accepted echoes • A large number of sub-carriers (like in 8k): • small inter-carrier spacing but a large symbol duration • In short, the choice of the sub-carrier number has no impact on the broadcast capacity but on the trade-of between Doppler acceptance and maximum echo delays

8. DVB-H mission • Make it “… possible to transmit in one DVB transport stream both DVB-H and DVB-T components in such a way that existing DVB-T receivers which cannot decode the DVB-H portion are not disturbed by this DVB-H portion.”

9. Timesliced: • Service 1 • Service 2 • Service 3 • Not timesliced: • Service 4 1 2 3 1 2 3 1 2 3 1 2 4 DVB-H system elements • Time slicing for power saving • Time between the bursts gives the power saving (off time) • MPE-FEC for performance • 4k mode was chosen to provide mobility in medium SFNs • Extended TPS bits for efficient signaling MPE = Multiprotocoll encapsulationFEC= Forward Error CorrectionSFN= Single Frequency Network

10. IP Datacast (IPDC) • “IP datacasting is a service where digital content formats, software applications, programming interfaces and multimedia services are combined through IP (Internet Protocol) with digital broadcasting.” <http://www.ipdc-forum.com/about/> • All content delivered as IP packets • Connectivity layer convergence • DVB-H combined with IP datacasting enables distribution of many kinds of digital content • TV broadcast, music, games etc.

11. DVB-T ETS 300 744 8k, 2k Time Slicing MPE FEC DVB-T RF in IP-out , 4k, TPS DVB-H CODEC DVB-T and DVB-H coexistence

12. IPDC over DVB-H business • New forms of multimedia enjoyment for consumers • New market opportunities for telecommunication and broadcasting industries • High bandwidth and high transmission speeds but insensitive to number of recipients  attractive from a business perspective IPDC = IP Datacast

13. Network Design Flexibility & Signaling • Different datacast network operator and cellular network operator • Digital broadcast infrastructure • More transmission sites than normal broadcast networks required, but less than normal cellular phone networks – existing masts can be reused • Cellular networks used for payment and administrative data • Cellular network and broadcast network can share same core network Mobile Operator ISP UTMS Base station Core DVB-T Broadcasters DVB-H transmitter IP Backbone Mux DVB-H Broadcasters Broadcast operator

14. Cost efficient delivery of broadcast content to a large audience Low time to market Low complexity Not heavily affected of peak usage (during special events etc.) Flexible transport stream sharing between DVB-T and DVB-H possible Based on DVB-T with minimal changes Fulfils most commercial requirements Allows seamless handover No adverse effect on DVB-T IP allows encryption DVB-H features/pros

15. DVB-H features/cons • Only IP based services possible • Reduced power saving when total bit rate for DVB-H services is very low (no big “bursts” possible)

16. Mobile Terminal • FE = Front End, contains radio receiver and demultiplexor FE CPU Media decoder Display WLAN Cellular Link

17. Power consumption and handover • IP encapsulation allows sending the data in bursts to the mobile station and this saves energy (battery power) • Power consumption and handover • 2 Mbit buffer • Handover possible during off time (services can be used even if the terminal has moved during off time)

18. C/N Performance • RS decoder utilizing the Time Slice buffer • Virtual time interleaver • 10% TS PER tolerated • Doppler and CN improved in mobile and portable • Impulse interference tolerance improved • Possibility to vary the level of robustness

19. Nokia’s 7700 with support for DVB-H “The Nokia 7700 will support the Nokia Streamer SU-6 accessory, the first mobile IP Datacast receiver designed to demonstrate the mobile phone television experience using the DVB-H network. The Nokia Streamer can be attached to the Nokia 7700 like a battery pack, and will be used in pilot projects to showcase the future of digital broadcasting on mobile devices.” <http://press.nokia.com/PR/200310/922406_5.html>

20. References • DVB-H – digital TV for handhelds? Jukka Henriksson, Nokia • Content Distribution Using Wireless Broadcast and Multicast Communication Networks. Janne Aaltonen, Thesis for Degree of Doctor, Tampere University of Technology • IP Datacasting Technology - Bringing TV to the Mobile Phone, White Paper <http://www.nokia.com/BaseProject/Sites/NOKIA_MAIN_18022/CDA/Categories/AboutNokia/Press/WhitePapers/_Content/_Static_Files/ipdatacastingtechnology.pdf> • DVB <http://www.dvb.org/index.php?id=20> • Cable & Satellite International <http://www.cable-satellite.com/main_news.htm> • Sonera medialab <http://www.medialab.sonera.fi/projects/ipdcmhp/ > • EE-Times Junko Yoshida, <http://www.eetimes.com/sys/news/OEG20030310S0049> • Performance analysis and low power VLSI implementation of DVB-T receiver<http://www.signal.uu.se/Courses/Semabstracts/ofdm2.pdf> • DVB-T: New Operative Modes For Digital Terrestrial TV, Gerard Faria, <http://www.broadcastpapers.com/tvtran/HarrisDVBTNewOpModes.doc>