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 Multiplexing C/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. 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 encapsulation FEC= Forward Error Correction SFN= Single Frequency Network Timesliced: Service 1 Service 2 Service 3 11 1122 22 3 33 4 Not timesliced: Service 4

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.” –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 and DVB-H coexistence DVB-H CODEC Time SlicingMPE FEC DVB-T ETS 300 744 8k, 2k, 4k, TPS DVB-T RF inIP-out

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 UTMS Base station DVB-H transmitter ISP DVB-T Broadcasters Core Mux Mobile Operator Broadcast operator IP Backbone DVB-H Broadcasters

14. DVB-H features/pros 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

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 WLAN Cellular Link CPU Media decoder Display

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.”

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 DVB Cable & Satellite International Sonera medialab EE-Times Junko Yoshida, Performance analysis and low power VLSI implementation of DVB-T receiver DVB-T: New Operative Modes For Digital Terrestrial TV, Gerard Faria,