DVB-H - Digital Video Broadcasting for Handhelds - Digital Video and Audio Broadcasting Technology - page 425

value 0x78 as Table_ID. The header of these FEC sections has the same
structure as that of the MPE sections. Due to the separate transmission of
the FEC, a receiver is capable to retrieve the IP packet even without FEC
evaluation if there are no errors. Furthermore, the IP information to be
transmitted is combined into time slots in the MPEG-2 transport stream.
In the time slots, the time t until the beginning of the next time slot is
signalled in the DSM-CC header. After receiving a time slot, the mobile
telephone can then "go to sleep" again until shortly before the next time
slot in order to save battery power. On average, the data rates in the time
slots will be up to about 400 kbit/s, depending on application. This is IP in-
formation requested simultaneously by many users. To signal the time t
until the next time slot, 4 of the total of 6 bytes provided for the destination
MAC address in the DSM-CC header are used. The end of a time slot is
signalled via the frame boundary and table boundary bit in the MPE and
FEC sections (Fig. 22.8.). The mobile receiver is notified about where an
IP service can be found by means of a new SI table, the IP MAC Notifica-
tion Table (INT) in the MPEG-2 transport stream. The time slot pa-
rameters are also transmitted there (Fig. 22.8.).

191
columns

64
columns

Reed
Solomon

n
rows

IP datagrams

MPEFEC
DSMCC
sections
(Table_ID=0x78)

DSMCC sections
(Table_ID=0x3E)

Fig. 22.7. MPE and FEC sections in DVB-H

Instead of the least significant 4 MAC address bytes, the MPE section in
DVB-H contains the time slot parameters, the time t until the beginning
of a new time slot in 10-ms steps, and the two "table_boundary" and "fra-
me_boundary" bits. "table_boundary" marks the last section within a time
slice and "frame_boundary" marks the real end of a time slice, especially
when MPE FEC sections are used.