Digital Audio Broadcasting - DAB - Digital Video and Audio Broadcasting Technology - page 490

flexible use of the subchannel. It is possible to embed different data ser-
vices and to provide variable data rates.
In the following section, the structure and content of the Fast Informa-
tion Channel (FIC) and of the Main Service Channel (MSC) will be con-
sidered in greater detail. The information transmitted in the fast informa-
tion channel and main service channel come from the Main Stream Data
(MST) from the Ensemble Transport Interface (ETI). FIC and MSC are
provided with error protection (FEC) in the modulator, the FIC being
given the strongest protection. The error protection in the MSC is config-
urable. The strength of the error protection in the MSC is signalled to the
receiver in the FIC.

FIC

FIC=Fast Information Channel

FIB … FIB

FIB=Fast Information Block

FIB =
256 bit with
16 bit CRC

FIB data field CRC

…

FIG n FIG m

Padding

FIG=Fast Information Group

FIG type Length FIG data field

Fig. 26.27. Structure of the DAB FIC

In the MSC, the individual subchannels are transmitted, a total of 64
subchannels being possible. Each subchannel can be error-protected to a
different degree which is also signalled in the FIC. The subchannels are
combined or more precisely allocated to services.
The Fast Information Channel is not time interleaved but transmitted er-
ror protected in so-called Fast Information Blocks (FIB).
In the FIC the Multiplex Configuration Information (MCI) is transmit-
ted which is information about the composition of the multiplex data
stream, as well as the Service Information (SI) and the Fast Information
Data Channel (FIDC).