During transmission of the OFDM
signal, the
symbols
will be multiplied by the
window
*w*(*t*) and not
by

*w*^{ }(*t*). The spectra of the pulses *w*(*t*) have no zero crossings at integer values of 1 T as it happens with *w*^{ }(*t*)

it only happens for the particular case of the rectangular window, because in this case *w*(*t*) = *w*^{ }(*t*) . The orthogonality is achieved at the receiver side by multiplying the incoming signal by *w* (*t*). The information sequence *A*_{k }is obtained after multiplication by the corresponding complex conjugated phasor and integrating
over an interval T(1+a_{r}), as shown in Figure
2.13. In Figure 2.14, the spectrum of an OFDM signal with *A*_{k}

*k *and N=32 is represented. There it can be better appreciated the dependency of the total bandwidth of the OFDM signal with respect to the selected window. Clearly, the root raised cosine (RRC) window results in
the better bandwidth efficiency among the proposed windows.