Queries Reg -OFDM transceiver Implementation

Hi,


   I'm working in OFDM transceiver implementation in FPGA. I have
following doubts. Kindly clarify .

1) How to determine number of points in IFFT with respect to bandwidth?

2) For given 1 MHz Bandwidth , what is the maximum amount of bandwidth
that can be allowed for not having ISI and cross symbol interference.

3)How Receiver will take care of Doppler shift?

Thanks 

On Oct 22, 11:56&#4294967295;pm, "Ammankumar" <s.ammanku...@gmail.com> wrote:

> 1) How to determine number of points in IFFT with respect to bandwidth?

The bandwidth depends on the sample rate (assuming all subcarriers are
used).
You can have as many points in the IFFT as you want - it simply
increases the length of an OFDM symbol at a given sample rate.

> 2) For given 1 MHz Bandwidth , what is the maximum amount of bandwidth
> that can be allowed for not having ISI and cross symbol interference.

Your questions does not really make sense.
Complete elimination of ISI and CSI relies on having an adequately
long cyclic prefix (guard interval), correct sample timing, correct
shaping filters, no doppler (see below), etc - so that the symbols do
not interfere despite the dispersive channel, and so the subcarriers
within each symbol retain their orthogonality. It has nothing to do
with the bandwidth as such.

> 3)How Receiver will take care of Doppler shift?

This is quite a serious problem for OFDM - there are various methods
in the literature which I suggest you research.

-T