Digital Video Mobile Broadcast (DVB-H) Specification

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The DVB-H specification includes:

Time-Slicing Rather than continuous data transmission as in DVB-T, DVB-H employs a mechanism where bursts of data are received at a time – a so-called IP datacast carousel. This means that the receiver is inactive for much of the time, and can thus, by means of clever control signalling, be "switched off". The result is a power saving of some 90% and more in some cases.

4K-mode With the addition of a 4K mode with some 3409 active carriers, DVB-H benefits from the compromise between the high speed small areas SFN capability of 2K DVB-T and the lower speed but larger area SFNs of 8K DVB-T. In addition, with the aid of enhanced in-depth interleavers in the 2K and 4K modes, DVB-H has even better immunity to ignition interference.

MPE-FEC The addition of an optional, multiplexer level, forward error correction scheme means that DVB-H transmissions can be even more robust. This is advantageous when considering the hostile environments and poor (but fashionable!) antenna designs typical of handheld receivers.

Compatibility with DVB-T

Like DVB-T, DVB-H can be used in 6, 7 and 8 MHz channel environments. However, a 5MHz option is also specified for use in non-broadcast environments. A key initial requirement, and an amazing feature of DVB-H, is that it can co-exist with DVB-T in the same multiplex. Thus, an operator can choose to have 2 DVB-T services and one DVB-H service in the same overall DVB-T multiplex.

What of ATSC and ISDB-T?

2004 is all about mobile and portable multimedia. This sidelines the single carrier (8-VSB) ATSC system from the US. ISDB-T, developed and now deploying in Japan has a mode which could offer mobile datacasting services, but concerns about battery power, receiver cost and system complexity remain.

DVB-T is deployed in some 50 countries and, with DVB-H, now provides a powerful tool to address new markets for DVB services.


 

DVB-H Technical Specifications:

DVD-H is based on the DVB-T standard, but is backwards fully compatible

DVB-H gives additional features to support Handheld portable and mobile reception, such as:

•battery saving

•mobility with high data rates, single antenna reception, SFN networks

•impulse noise tolerance

•increased general robustness

•support for seamless handover

•The above have been achieved by adding options

•Time-slicing for power saving

•MPE-FEC for additional robustness and mobility

•4k mode for mobility and networkdesign flexibility

•plus additional minor changes, e.g., in signalling

•DVB-H is meant for IP-based services via MPE insertion

•DVB-H can share DVB-T multiplex with MPEG2 services

•Portable/indoor coverage should be built to the network for fully exploit the DVB-H possibilities businesswise

Some Basic Facts of Mobile Reception:

  • The DVB-T standard could be used as it is but DVB-H would give more flexibility•

  • The Doppler tolerance in 8k is worse than 2k. (4k is a nice compromise).

  • Additional MPE-FEC of DVB-H increases performance.•

  • The DVB-T Interleavers are not very long, as they are optimised for fixed reception.

  • DVB-H gives more interleaving.•

  • The lower constellations (QPSK,16QAM) tolerate fair amount of Doppler and require reasonable C/N.

  • The code rates ½ and 2/3 most suitable•Both MFN and SFN topologies can be used.

  •  Transmitter frequency is an important parameter for maximum speed.

 
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