Design of Antennas for Handheld DVB-H ... - Lunds tekniska högskola

Every section has information in the header about start address for the IP
datagram. The address indicates the position for the first byte of the IP datagram
in the application table. This application data is followed by the parity bytes in the
RS data table that are read out column by column and encapsulated in separate
MPE-FEC sections. The FEC frame structure also contains a block interleaving
effect in addition to coding. That means that the receiver can put the datagram in
right order in the application table and mark it “reliable” for the RS decoder. A
flag marks the end of the application data table. If all application data is received
correctly none of the MPE-FEC sections are necessary. That is optimal if time
slicing is used, because then the receiver can go to sleep [17].
2.1.5.5 4K mode
Figure 2.6. The MPE-FEC frame.
DVB-T provides two different modes for different topologies, 2K and 8K mode.
DVB-H also disposes of an intermediate 4K mode that has a little of both 2K and
8K modes qualities. The qualities of the different modes can be seen in Table 2.1.
It allows twice as long distance between receiver and transmitter in SFNs
compared to the 2K mode and it is less susceptible to Doppler frequencies in case
of mobile reception compared to the 8K mode. The 4K mode shall make the
network planning for DVB-H easier, this does not apply for DVB-T since it does
not include the 4K mode [10].
To make transmissions with the 4K mode possible a new symbol interleaver with
4096 OFDM carrier frequencies was specified. In connection with the three
network modes a new symbol-interleaving scheme is defined (See figure 2.7). A
DVB-H terminal should support all three modes and then needs an 8K symbol
interleaver. It is preferred to use the relatively big memory of the 8K symbol
interleaver in all three network modes. This symbol interleaver is able to process
the amount of one complete 8K OFDM symbol or alternatively two 4K OFDM
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