Error probability of QASK with rectangular and circular symbol constellations in the presence of intersymbol quadrature channel and adjacent channel interference

In the paper we study the effect of intersymbol, quadrature channel and adjacent channel interference (in addition to Gaussian noise) on the error probability of M-ary quadrature amplitude modulation (QAM) with M = 4, 16 symbols and phase shift keying (PSK) with M = 4, 8 and 16 symbols, which are special cases of quadrature amplitude shift keying (QASK) with a rectangular and circular constellation. The transfer function of the system for the main signal is a raised cosine with excess bandwidth ¿¿, and the receiver filter is matched to the transmitter filter. The interfering signal is of the same type as the main signal, but its carrier frequency differs from the carrier frequency of the main signal by the frequency fs. In the paper we also present the necessary formulas for the computation of error probability in the presence of frequency selective fading.