Digital Signal Processing Reference
In-Depth Information
These are:
•
Time slicing on/off in the MPEG-2 transport stream (=DVB-H)
•
IP FEC on/off
•
In-depth interleaving on/off
•
4K mode
For this purpose, 2 additional bits from the reserved TPS (Transmission
Parameter Signalling) bits, bits 42 and 43, and bits already used are used.
The details can be found in Fig. 22.5.
Using the 4K mode and in-depth interleaving in the 4K and 2K mode al-
lows a better RF performance to be achieved in the mobile channel. At the
same time, the achievable transmitter spacing in 4K mode (approx. 35 km)
is greater by a factor of 2 compared with the 2K mode (approx. 17 km) in
an SFN network.
Apart from the 8, 7 or 6 MHz channel known from DVB-T, a bandwidth
of 5 MHz (L band, USA) can now be selected in DVB-H.
The other modifications are found in the structure of the MPEG-2 trans-
port stream.
Burst n
Burst n + 1
Delta t
MPEG2 TS
MPE sections (DSMCC),
MPEFEC sections
Fig. 22.6.
Time slicing in DVB-H
In DVB-H, IP transmission is achieved via the MPEG-2 transport
stream by means of the Multiprotocol Encapsulation (MPE) already de-
scribed. Compared with conventional MPE, however, there are some spe-
cial features in DVB-H: the IP packets can be protected with an additional
Reed Solomon FEC (Fig. 22.7.). The Reed Sololomon FEC of an IP data-
gram is transmitted in its own MPE FEC sections. These sections have the
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