>On Jun 18, 11:43=A0am, "san3885" <santosh.3...@gmail.com> wrote:
>> >On Jun 17, 8:44=3DA0pm, Porterboy 76 <porterbo...@gmail.com> wrote:
>> >> > One more thing ,in a particular system 64 pt IFFT/FFT was take
.in
>> >> > which 52 were carriers(48 data + 4 pilots) rest were zeros.
>> >> > and 16 CP.
>>
>> >> This is from the IEEE 802.11 Standard.
>>
>> >ya but i want to know whats the advantage of padding zeros .
>>
>> Hi,
>> Zero padding increases the sampling rate. In other words the resolutio
o=
>f
>> the signal increases...
>> Where as CP provides resistance against inter symbo
interference..(ISI)
>>
>> Good Luck..
>
>hi
>you sure about it.Interpolation increases sampling freq , thats
>true,but here we aren't doing the same we are appending zeros at the
>end.
>Will it really increase the resolution?
>
>
No. Resolution increases only if you pad zeros in the middle (in frequenc
domain).
Are you padding zeros to both the ends or to any one ?
If you add to both the ends it will serve as guard band as well...
Also, i observe in your example above..

Data + Pilots = 52 freq bins
52 is not a power of 2, hence you cant perform IFFT/FFT operation on it.
Otherwise its a mess to perform N-point DFT/IDFT in hardware.
I think this is one of the main reason for zero pad.
May be someone can throw more light on this...