Multicast over DAB

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Multicast over DAB

• Fredrik Nilsson
• Mikael Larsson
• Seminar
• based on Teracom report
• written in march 2000

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Multicast over DAB

• What is DAB?
• Digital Audio Broadcast (Digital Radio)
• Can also be used for TV
• Arlanda Express uses DAB for receiving files for
  the news system on board
• SR have been using DAB since 1995

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Multicast over DAB

• DAB transmission speed between 32 kbit/s and 384
  kbit/s.
• Normal DAB samplerate 48kHz (Same as normal DAT)
• Coded Orthogonal Frequency Division Multiplex

4
Multicast over DAB

• Multicast not heavily deployed on the Internet
• Reasons
• Internet infrastructure is built based on point
  to point communication, not point to multi-point.
• ISP's sees no need to introduce the technology
• ...

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Multicast over DAB

• Why use a technology that has not gain foothold
  anywhere else?
• Reasons
• Broadcast networks is like a large ethernet
  ("...a wet dream for any person involved in IP
  multicast...")
• Broadcast networks are point to multi-point
  oriented
• Products adopted for multicast can be used more
  or less off the shelf

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Multicast over DAB

• Can any multicast protocol be appliceable with
  DAB? Answer NO!
• DAB has no interaction channel and hence can not
  send i.e. NACK's

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Multicast over DAB

• Can a reliable multicast protocol be applicable
  with DAB? Answer YES!
• FEC (Forward Error Correction) based protocols
  can be used to achive this