FFT in OFDM

hi all,

I have a question regarding FFT in OFDM. why do we use FFT in OFDM systems?

thanx.

srikoll wrote:

> I have a question regarding FFT in OFDM. why do we use FFT in OFDM
> systems?

To spread the data in time. And because its faster than a DFT.....

/Jesper

"Jesper Toft" <news@bzImage.dk> wrote in message
news:3fc7e693$0$9834$edfadb0f@dread14.news.tele.dk...
> srikoll wrote:
> > I have a question regarding FFT in OFDM. why do we use FFT in OFDM
> > systems?
>
> To spread the data in time. And because its faster than a DFT.....

More fundamentally, no feasible way to apply multi-carrier modulation on
OFDM symbols except using DFT and FFT.

-- 
Best regards,
James K. (txdiversity@hotmail.com, http://home.naver.com/txdiversity)
- Any remarks, proposal and/or indicator to text would be greatly respected.
- Private opinions: These are not the opinions from my affiliation.

On Sun, 30 Nov 2003 01:17:14 +0900, "James K."
<txdiversity@hotmail.com> wrote:

>"Jesper Toft" <news@bzImage.dk> wrote in message
>news:3fc7e693$0$9834$edfadb0f@dread14.news.tele.dk...
>> srikoll wrote:
>> > I have a question regarding FFT in OFDM. why do we use FFT in OFDM
>> > systems?
>>
>> To spread the data in time. And because its faster than a DFT.....
>
>More fundamentally, no feasible way to apply multi-carrier modulation on
>OFDM symbols except using DFT and FFT.
>
>-- 
>Best regards,
>James K. (txdiversity@hotmail.com, http://home.naver.com/txdiversity)
>- Any remarks, proposal and/or indicator to text would be greatly respected.
>- Private opinions: These are not the opinions from my affiliation.

Even more fundamentally:  because the FT provides an easy mechanism
for assuring that the subcarriers are orthogonal.

Eric Jacobsen
Minister of Algorithms, Intel Corp.
My opinions may not be Intel's opinions.
http://www.ericjacobsen.org