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DVB-H. digital video broadcasting for handheld devices Björn Forss Magnus Melin. Introduction. Convergence of digital media and communication give users possibility to consume most digital content also in mobile environment

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dvb h

DVB-H

digital video broadcasting for handheld devices

Björn Forss

Magnus Melin

introduction
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 
motivation for creating dvb h
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

dvb t
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

dvb t 2
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
mobile reception of dvb t
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
2k 4k or 8k and why
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
dvb h mission
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.”
dvb h system elements

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

ip datacast ipdc
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.
dvb t and dvb h coexistence

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
ipdc over dvb h business
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

network design flexibility signaling
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

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

DVB-H features/pros
dvb h features cons
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)
mobile terminal
Mobile Terminal
  • FE = Front End, contains radio receiver and demultiplexor

FE

CPU

Media

decoder

Display

WLAN

Cellular

Link

power consumption and handover
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)
c n performance
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
nokia s 7700 with support for dvb h
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>

references
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>
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