power spectrum of passband of ofdm is it right shape or not?
Doesn't look right. a 64-FFT with only the center 52 carriers occupied should look pretty &quot;rectangular&quot;.
I'd recommend not doing the upconversion. OFDM is designed to be an equivalent-baseband system, so you can definitely investigate whether your OFDM works directly in baseband. It's way more intuitive that way.