As presented earlier as long as the base station time
differential plus delay spread is less than the CP the DVB-H system is operating properly.
486 CHAPTER NINE
User
#1
Burst
User
#1
OFF Time
Burst
Bit
Rate
t
User
#2 User
#3
User #4
User
#2 User
#3
FIGURE 9.9 DVB-H and DVB-T transmission example.
Broadcasting of the ???cell identifier??? is mandatory in DVB-H and is used to help identify neighboring
network with same services as the present one.
MPE-FEC adds another layer of error correction by adding additional parity information to the
data to be transmitted. This is accomplished by using the Reed-Solomon RS(255,191) outer FEC code
with error correction capability of t 32 bytes. MPE-FEC is optional in DVB-H.
The DVB-H system is IP based hence the interface to higher layers is an IP interface. Since
MPEG-2 transport streams are still the standard DVB interface, an adaptation protocol is needed.
MPE is a protocol used to encapsulate multiple IP streams into the MPEG-2 DVB-T transport stream.
For file download services Raptor FEC codes are applied in the application layer [27]. MPE-FEC is
disabled when Raptor FEC is used.
The DVB-T supports 2K (2048) and 8K (8192) FFT sizes. DVB-H adds a 4K (4096) FFT size mode.
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