>Hi,
>
>This has been a very informative forum while i have been working on this
>small simulation. I have a couple of questions now.
>
>1) First I am simulating a simple uncoded 16-QAM OFDM system. I tried
>evaluate the performance of such a system in an AWGN channel and the
>results i have matches results of a single carrier system using 16 QA
in
>a AWGN channel.
>
>2) Now I would like to study the effects of cyclic prefix in an OFDM
>system and do that i have made the necessary modifications to my
>transmitter and receiver. Specifically, i add the cyclic prefix at the
>transmitter pass it through a multipath channel, remove the cycli
prefix
>at the receiver before the FFT operation at the receiver.
>
>3) The multipath channel i consider have static paths ( No fading, No
>Dopper ).
>
>My question is : For such an uncoded system what channel impuls
response
>can i consider whereby i can see the benefits of the cyclic prefix.
>A comparison of channel impulse response vs prefix lengths ( greate
and
>less than impulse response length) is what i have in mind.
>
>Also, I am not clear on what sort of compensation needs to be done a
the
>receiver for the channel. If we assume perfect knowledge of the channe
at
>the receiver an operation of the form FFT(Y)./FFT(h) would suffice ?
where
>Y is the received signal before FFT operation and h is the impulse
>response
>
>
>Thanks
>
>

Hi, As long as the delay spread of channel is less than CP length
multipath won't affect performance. But you have to consider if the pea
does not appear at the very beginning, then there might still be some IS
"leaking" from backwards.