Digital Video Broadcasting for Handheld devices(DVB-H)

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Digital Video Broadcastingfor Handheld
devices(DVB-H)
Sahar Aghayan 6592207 sagha012_at_uottawa.ca
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Digital video Broadcasting(DVB)
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Digital video Broadcasting(DVB)
Digital Video Broadcasting-Satellite(DVB-S) In
DVB-S, the signal is broadcasted through the
satellite. Digital Video Broadcasting-Cable(DVB-C)
In DVB-C, the signal is broadcasted through the
broadband coaxial cable.  Digital Video
Broadcasting-Terrestrial(DVB-T) In DVB-T, the
signal transmitted using terrestrial
methods. Digital Video Broadcasting-Handheld(DVB-H
) In DVB-H, the broadcast services are given to
the mobile handsets.
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DVB-T

• Terrestrial Digital Television Standard
• Used in 36 countries world wide
• One-to-many broadband wireless data transport
• Developed for MPEG-2 stream distribution, but can
  basically carry any data
• DVB-T includes hierarchical modes where two
  transport streams can be sent simultaneously

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DVB-H

• Digital Video BroadcastingHandheld (DVB-H)
  standard is based on
• the earlier standard DVB-T, which is used for
  terrestrial digital TV broadcasting.
• It Brings features that make it possible to
  receive digital video broadcast type services in
  handheld, mobile terminals.

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DVB-H

• A full DVB-H system is defined by combining
  elements in the physical and link layers as well
  as service information. DVB-H makes use of the
  following technology elements for the link layer
  and the physical layer
• Link layer
• time-slicing
• -To reduce the average power
  consumption of the terminal
• - smooth and seamless frequency
  handover
• forward error correction for multiprotocol
  encapsulated data (MPE-FEC)
• - improvement in C/N-performance and
  Doppler performance in mobile channels
• - improving tolerance to impulse
  interference.

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DVB-H

• Physical layer
• DVB-H signalling in the TPS(Transmission
  Parameter Signalling)-bits
• - enhance and speed up service
  discovery
• - Cell identifier is also carried on
  TPS-bits to support quicker signal scan and
  
• frequency handover on mobile
  receivers
• 4K-mode
• - for trading off mobility and
  SFN(Single Frequency Network) cell size,
• - allowing single antenna reception in
  medium SFNs at very high speed, adding thus
  flexibility in the network design
• in-depth symbol interleaver for the 2K and
  4K-modes
• - for further improving their robustness in
  mobile environment and impulse noise conditions.

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DVB-H Reciever
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DVB-HTime Slicing

• Reduce the average power consumption of the
  terminal (up to about 9095)
• Enable smooth and seamless service handover.
• Sending data in bursts
• On and Off time(Power safe Mode)
• Possibility to monitor neighbouring cells during
  the off-times
• Transmitter is constantly on
• Mandatory in DVB-H.
• Time between the bursts gives the power saving
  (off time)

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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
• Handover possible during off time (services can
  be used even if the terminal has moved during off
  time)

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IP packets in DVB-H

• DVB system can be used for transmission of IP
  packets. This is done by
• Multiprotocol Encapsulation (MPE)
• DVB-H uses exclusively IP packets for media
  transfer

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Multiprotocol Encapsulation

• IP packets are embedded into MPE sections which
  are put into TS
• packets

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DVB-HMPE-FEC

• FEC for multiprotocol encapsulated data (MPE-FEC)
• gives an improvement in carrier-to-noise (C/N)
  performance
• and Doppler performance in mobile channels
• Immunity to impulse interference.
• By adding parity information calculated from the
  datagram and sending them in separate MPE-FEC
  section, error-free datagrams can be output from
  MPE-FEC decoding despite a very bad reception
  condition
• MPE-FEC is optional

MPE-FEC frame structure
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DVB-H in-depth interleaver

• Interleaving is a technique where sequential data
  words or packets are spread across several
  transmitted data bursts. In this way, if one
  transmitted burst or group is lost as a result of
  noise or some other drop-out, then only a small
  proportion of the data in each original word or
  packet is lost and it can be reconstructed using
  the error detection and correction techniques
  employed.
• Using the in-depth interleaver enables the noise
  resilience performance of the 2K and 4K modes to
  be brought up to the performance of the 8K mode
  and it also improves the robustness of the
  reception of the transmissions in a mobile
  environment.

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Conclusion

• features/pros
• Cost efficient delivery of broadcast content to a
  large audience
• Low time to market
• Low complexity
• 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

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Conclusion(2)

• 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)(Max 2Mb)

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Question1.

• DVB-H, as a transmission standard uses a
  power-saving algorithm(Time-slicing) based on the
  time-multiplexed transmission of different
  services. With considering 20 services to be
  transmitted and The MPEG-2 TS have a bitrate of
  10 Mb/s. How much would be the off-time for a
  receiver in DVB-H? Compare the situation for
  DVB-T?
• (Note the Maximum burst value is 2 MB)

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Q1.Aswer

• In time-slicing IP-services within a MPE data
  service are organised
• One service will use the full DVB-H data
  capacity for a while, say 200 ms(burst time).
• After that comes the next service and so on
• After longer period, say 4s, the first service
  is again in the air.
• Ott-timerelative time difference between two
  consecutive bursts of the same service

On Off
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Q1.Answer

• In normal DVB-T MPEG-2 and data transmissions
  the transport streams from the services are
  multiplexed together with high frequency on the
  TS-packet level.
• This means that the services are transmitted
  practically in parallel.
• For a DVB-T receiver it is impossible to receive
  only the wanted TS-packets due to the high
  multiplexing rate. All data must be received -gt
  high power consumption.

Channel Capacity
time
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Question2.

• Adding 4K transmission mode in DVB-H aims to
  offer an additional trade-off between Single
  Frequency Network (SFN) cell size and mobile
  reception performance. Please explain in detail
  the terms of this trade-off compare to 2k and 8K
  mode?

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Q2. Answer

• 8K mode can be used both for single transmitter
  operation and for small, medium and large SFNs.
  It provides a Doppler tolerance allowing high
  speed reception.
• 4K mode can be used both for single transmitter
  operation and for small and medium SFNs. It
  provides a Doppler tolerance allowing very high
  speed reception.
• 2K mode is suitable for single transmitter
  operation and for small SFNs with limited
  transmitter distances. It provides a Doppler
  tolerance allowing extremely high speed
  reception.

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Question3.

• suppose we have the following four bytes of data
  D110100101, D211110000, D3 00111100, and
  D410111001,
• a) Calculate the parity data.
• b) Suppose we have received D1, D2, and D4 at
  the receiver. How we can retrieve D3 data?

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Q3. Answer

• HINT
• Parity information calculated from the block of
  data can be used to reconstruct the block of data
  in the event of data loss or failure.
• The parity calculation is typically performed
  using a logical operation called "exclusive OR"
  or "XOR
• Given Property  "A XOR B XOR B A"

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Q3. Answer

• A) Answer
• D1 XOR D2 XOR D3 XOR D4 ( (D1 XOR D2) XOR D3)
  XOR D4 ( (10100101 XOR 11110000) XOR 00111100)
  XOR 10111001 (01010101.XOR 00111100) XOR
  10111001 01101001 XOR 10111001 11010000
• b) Answer
• D1 XOR D2 XOR D4 XOR DP ( (D1 XOR D2) XOR D4)
  XOR DP ( (10100101 XOR 11110000) XOR 10111001)
  XOR 11010000 (01010101 XOR 10111001) XOR
  11010000 11101100 XOR 11010000 00111100

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Thank YouAny Question!