Hi all,
I'm working on the Matlab Simulink DVB-T demos (2k). I'd like to
understand:
After the IFFT block, the frames composed by 2048 data samples ( or
elementary symbols of 7/64us duration) are sent to the AWGN channel.
But, according the standard ETSI EN 300 744 v.1.12 (1997-08) on which the
model is based, an OFDM symbol should be composed by 2176 elementary
symbols (2048+128 of Guard Interval). It means that in this model there is
no guard intervals?  So I should include a new Guard Interval Block? 
thanks in advance for your help
Raffaele

Raf said the following on 31/08/2006 12:16:
> Hi all,
> I'm working on the Matlab Simulink DVB-T demos (2k). I'd like to
> understand:
> After the IFFT block, the frames composed by 2048 data samples ( or
> elementary symbols of 7/64us duration) are sent to the AWGN channel.
> But, according the standard ETSI EN 300 744 v.1.12 (1997-08) on which the
> model is based, an OFDM symbol should be composed by 2176 elementary
> symbols (2048+128 of Guard Interval). It means that in this model there is
> no guard intervals?  So I should include a new Guard Interval Block? 

A guard interval (in the form of a cyclic prefix) is only needed in a 
frequency-selective channel.  In a simulation using only AWGN, it would 
be a waste of time to simulate the guard interval.




-- 
Oli