If the bit rate of the digital communication system is 'R' Kbps & the modulation used is 32-QAM, what is the minimum bandwidth required for ISI free transmission?
My understanding & analysis so far:
QAM (a digital-to-analog conversion technique) is a combination of ASK & PSK. The idea behind QAM is to alter two characteristics (amplitude & phase) instead of just one to improve the bit rate.
From literature (Data Communications & Networking by Forouzan), the minimum bandwidth required for QAM is same as that of ASK/PSK.
BW for Binary ASK is given by B = (1+d)S, where S is the signal rate.
For 32-QAM bandwidth is
B = S = (bit rate)/(bits per signal element) = R/5 KHz
(for 32-QAM no. of symbols per signal element is log2(32) = 5)