This allows the network to have a trade-off of Doppler performance, mobility performance, cell size,
and spectral efficiency. The 2K FFT system can tolerate the highest Doppler spread of the three possible
values. However, it has a short guard interval preventing a large cell size deployment scenario. On
the other hand, the 8K transmission mode has a large guard interval and suffers in performance in high
Doppler spread cases. Lastly, a 5-MHz bandwidth has been added to the list of available BWs supported.
Symbol level interleaving has also been suggested to obtain better performance in channel conditions
with larger bursts of error. The interleaving is applicable to the 2K and 4K transmissions modes.
Lastly, DVB-H signaling is required to indicate the various parameters associated with the abovementioned
additional features.
A block diagram of a network providing DVB-H services is shown in Fig. 9.10 where each cell is
transmitting in a different frequency band (e.g., f1, f2, and f3).
In Fig. 9.11 we provide an example protocol stack and software architecture of the DVB-H system.
Note IP data can be sent over DVB-H through what is called IP data casting [26].
A few concerns should be addressed in such a broadcasting system.
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