On 6/17/2009 7:41 AM, priya wrote:
> Hi all,
> I have just started reading about the OFDM systems .I have read in
> some paper that zero padding is advantageous over Cyclic prefix
> approach.
> In most of the systems i have found Cyclic prefix there not zero
> padding.

There are some disadvantages to zero-padding instead of using a cyclic
prefix. It's been discussed here before, so maybe search around.

> ONe more thing ,in a particular system 64 pt IFFT/FFT was taken .in
> which 52 were carriers(48 data + 4 pilots) rest were zeros.
> and 16 CP.
> Is there any advantage of using 12 zeros?

You need a guard region to prevent aliasing around the edge subcarriers.
In other words, to use the edge subcarriers one would need a brickwall
anti-alias filter, and those don't exist.

> I could not find any reference for the same if any paper is there
> please send me the one.
> All i could make out is that it may reduce the PAPR.
>
> With regards
> pria