Presentation of DVB-H I did for a seminar in 2007

1. DVB ­ H
Broadcasting to the Future
Mobile TV Data Transport
Hornsby Adrian

2. Introduction
DVB­H aims to provide digital TV reception to

mobile devices.
Combines traditional television broadcast

standards with elements specific to handheld
devices; mobility, smaller screens and
antennas, indoor coverage and reliance on
battery power .

3. DVB­T
Terrestrial Digital Television Standard

Used in 36 countries world wide
−
One­to­many broadband wireless data transport

Video, audio, data and – importantly – IP packets
−
Scalable: cell size up to 100km (DVB­H cell size is smaller)
−
Huge capacity: 54 channels each 5­32Mbit/s
−
Shut down of analog TV will free up huge frequency

capacity for DVB­T usage
Developed for MPEG­2 stream distribution, but can

basically carry any data, flexible
DVB­T = Digital Video Broadcasting ­ Terrestrial

4. DVB­T (2)
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 Salomon­Reed
−
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

5. OFDM
OFDM is the fashionable radio technique: WiFi,

WiMAX, DAB, DMB, …

6. 2k, 4k or 8k and why?
A small number of sub­carrier provides (like in 2k):

− large inter­carrier spacing ­> gives tolerance to the
echoes affected by Doppler
− short symbol duration ­>limits the maximum delay of
accepted echoes
A large number of sub­carriers (like in 8k):

− small inter­carrier spacing but a large symbol duration
In short, the choice of the sub­carrier number has no

impact on the broadcast capacity but is a new trade­off
between transmission cell size and mobile reception
capabilities, flexibility for network planning (Doppler
acceptance and maximum echo delays)

7. Motivation for creating DVB­H
Why not use UMTS?

Not scalable for mass content delivery
−
For delivery of mass media content, broadcast networks should be
−
preferred over point­to­point cellular networks
Why not use DVB­T?

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

8. DVB­H Standard
DVB­H
TS 101
EN 302 304 Implementation
191
DVB­H Guidelines
SFN
ETR XXX XXX
System
Megaframe
Specification
norminative
EN 300 468
EN 301 192
DVB SI
Data Broadcasting
­ Time Slicing
­ MPE­FEC
EN 300 744
DVB­T
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
­­­­­­
Annex F, G
­ TPS ­ 4k
­ Interleavers ­ 5 Mz

9. What is DVB­H ?
Transmission of Data mainly as IP frames

(Internet Protocol)
New video compression scheme (H.264) with

lower bitrate and for smaller screen size
approx. 390 Kbit/s per stream (MPEG2 3­4

Mbit/s)
More suitable for broadcasting to mobile

environment

10. Features of DVB­H
 Time Slicing : allow Power Saving and Frequency
Handover
 MPE­FEC : an additional protection at the DATA
link layer level
 New Signaling scheme : modified TPS bits and
more MPEG tables (INT)
 4K: a new trade­off between transmission cell size
and mobile reception capabilities, flexibility for
network planning


11. Time Slicing
Burst Transmission
●
Significant Power Saving (up to 90%)
●
Seamless Handover
●
Longer initial tunning delay Bust Size 2 Mbit
●
­> 2Mbit buffer
Off Time
Service 1
Service 1
Service 3
Service 4
Service 2
Service 5
Service 1
Service 2
Service 2
Service 3
Service 4
Service 5
DVB­H
DVB­T

12. MPE­FEC
 MPE­FEC (Forward Error Correction)
• Reed­Solomon coding on IP datagrams => higher error resistance
• Virtual interleaving, FEC placed in separate sections
• (receiver is free to ignore MPE­FEC)
Application Data Table RS Data Table
191 columns 64 columns
1024 rows (max.)
RS Codewords
IP Section FEC Section

13. Multiprotocol Encapsulation (MPE)
 MPE (Multi Protocol Encapsulation)
• IP encapsulated into MPEG­2 packets (traditional DVB )
• Mux­compatible with MPEG­2 TV services
40 ... 4080 bytes
IP datagram Header Payload
16 ...4095bytes
MPE sections Header Header Header Payload
Payload Payload
188 bytes
TS packets Header Header Header Payload
Payload Payload

14. Physical Layer Extensions
 Extension of Transmission Parameters Signalling (TPS).
 Reserved information channel with tuning parameters (Time­
sliced, MPE­FEC, cell­identifier, ...)
 Very robust signalling channel allowing TPS­lock in a
demodulator with very low C/N­values.
 Faster way to access signalling than demodulating and
decoding the Service Information (SI) or the MPE­section
header.

15. Transmission Parameters
All the DVB­T options including the new ones are available:

• 8k, 4k or 2k
• Modulations QPSK, 16QAM, 64 QAM
• Code rates 1/2­ 7/8, recommended 1/2 or 2/3
• Native or in­depth interleavers in 2k and 4k
MIKKO's recommendation ;)

16. DVB­H codec
RF signal
DVB­H modulator
QPSK
MPEG2 8K
TPS
DVB­H codec TS bits UHF
4K
MUX 16QAM (MPE­FEC,
amplifier
IP Time slicing,
Cell id ...)
2K
MPE­ Time
MPE
FEC Slicing 64QAM

17. PSI/SI and DVB­H
Transport Stream
PMT
PAT
Component 1
0x0000 Service 1 INT sub_table1
sub_table1
sub_table2
sub_table3
Service 2 Component 1 IP stream 1
NIT
IP stream 2
(actual network)
0x0010 IP stream 3
Component 2 IP stream 4
EIT
SDT IP stream 5
(actual TS)
(actual TS)
0x0012
0x0011 IP stream 6
Service 3 Component 1 IP stream 7
CAT TDT IP stream 8
IP stream 1
0x0001 0x0014
Component 2 IP stream 9
IP stream 10

18. DVB­H architecture (1/2)
DVB Network
network_id
Transport Stream 1
PSI transport_stream_id, original_network_id
Multiplex
PAT IP Platform 1
( PID 0x0000)
DVB Service 2 DVB Service 1
Component 3 Component 1
PMT INT sub_table 1
IP Stream 2
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
PMT sub_table 1 IP Stream 3
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
Component 2
PMT sub_table 2
IP Stream 1
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
........
SI IP Platform 2
NIT table DVB Service 3
Component 1 Component 2
(PID 0x0010)
INT sub_table 2 IP Stream 1 IP Stream 2
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
­
table_id 0x40
NIT_actual
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
­
table_id 0x41
NIT_other

19. DVB­H architecture (2/2)
DVB Network
network_id
Transport Stream 1
PSI transport_stream_id, original_network_id
Multiplex
PAT IP Platform 1
( PID 0x0000)
DVB Service 1
DVB Service 2 Component 1
Component 1 INT sub_table 1
PMT
IP Stream 1 IP platform 1
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
PMT sub_table 1
IP Stream 2 Component 2
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
INT sub_table 2
PMT sub_table 2
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
IP Platform 2
.........
SI IP Platform 2
DVB Service 3
NIT table Component 1 Component 2
(PID 0x0010)
IP Stream 2
IP Stream 1 IP Stream 2 IP Stream 3
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
­
table_id 0x40
NIT_actual
­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­
­
table_id 0x41
NIT_other

20. DVB­H Network
DVB Networks DVB Network
Multiplex 1 Multiplex 2 Multiplex 3
Transport Streams
DVB Services DVB Service 2
DVB Service 1 DVB Service 3
Elementary Streams Component 1 Component 2 Component 3

21. DVB­H Service Access
Signal Scan
Select TS
Best Signal Strength
Retrieve INT sub_table
for IP platform
Select IP Service (IP datagram stream)
usually from ESG
PMT sub_table
(service_id)
Elementary Stream
(component_tag)
Filter IP stream
based on IP address

22. DVB­H Protocol Stack
Application(s)
Audio,Video
3GP file format, Post repair
subtitling ...
Binary data, and reception
ESG Data
still images, reporting
RTP payload
SPP mechanisms
text, ... SPP
formats
(KSM,
(KMM)
KMM)
Streaming
HTTP
File Delivery (FLUTE)
(RTP/RTCP)
TCP
UDP
IP
DVB­H

23. DVB­H and the future hybrid networks
Broadcast Network
Cellular Networks
Wireless Networks