Zeph80 said the following on 09/03/2006 03:51:
> Well, the cylic prefix exists to combat ISI and the contents itself(tail of
> the symbol) lends itself to making the channel look like a circular
> convolution.So it really has a dual purpose, and my question is not the
> contents of the cylic prefix, but how its existence will remove ISI
>
>

To eliminate ISI, you need a time-domain guard interval in-between
blocks, which is longer than the length of the channel response.

i.e.

TX SIGNAL:

Block 1 Block 2
+---------+ +---------+
| | | |
| | | |
---+ +-----------+ +---------- -> t


RX SIGNAL: (Convolved with channel response)

Block 1 Block 2
+---------+ +---------+
| \__ | \__
| \_____ | \_____
---+ \-+ \ -> t
^
^
Blocks do not overlap.



The CP serves this purpose.


--
Oli