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IFFT in dvb-t

Started by Raf August 31, 2006
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