> The shaping of the CP is irrelevant when it comes to eliminating ICI.
L. Cimini in "Analysis and Simulation of a Digital Mobile Channel
Using Orthogonal Frequency Division Multiplexing" say "The act of
truncating the signal [ofdm symbol] to the interval (0, Ndt) [where N
is number of subcarriers, dt is the data bit time interval] imposes a
sinx/x frequency response on each subchannel with zeros at multiples
of 1/T [where T is defined as T = Ndt]. This spectral shape has large
sidelobes, and gives rise to significant interchannel interference in
the presence of multi-path."

They later go on to say "due to the use of the DFT, each subchannel
pssesses a sinx/x spectrum which has fairly large sidelobes, and which
may cause problems if the orthogonality of the subcarriers is
impaired. The sidelobes can be reduced ... by extending the frame of
data in time [i.e cyclic prefix] and by requiring gradual rather than
abrupt rolloffs of the transmitted waveform... shaped using a raised
cosine"

Which makes sense doesn't it? There will always be some loss of
orthogonality, so the lower the sidelobes are, the less they will
effect other sub-channels. So to me, the CP shaping does have an
effect on ICI.

Cheers
Andrew