Performance of SQAM systems in a nonlinearly amplified multichannel interference environment

The performance of superposed quadrature amplitude modulation (SQAM) systems, in a nonlinearly-amplified multichannel environment, in the presence of additive white Gaussian noise (AWGN), intersymbol interference (ISI), adjacent-channel interference (ACI) and cochannel interference (CCI), is investigated. This study is an extension of our previous work which was restricted to the performance study of SQAM modems in single-channel AWGN systems. Typical system configurations are analysed by means of computer simulations. Our results demonstrate that SQAM modems outperform OQPSK, MSK and IJF-OQPSK (or SQORC) modems.