Synchronization Error in QAM-Based FBMC System

We investigate the impact of the time offset (TO) and carrier frequency offset (CFO) on the performance of a filter bank multicarrier - quadrature amplitude modulation (FBMC-QAM) system. As opposed to conventional FBMC system where offset QAM (OQAM) is utilized due to the intrinsic interference, the FBMC-QAM system cancels the intrinsic interference based on the orthogonality conditions between the two kinds of filters. Because the FBMC-QAM system uses two kinds of filters, the effects on the TO and CFO are different compared to the conventional FBMC system. The performance of this system is degraded by TO because the two-filter orthogonality conditions are not satisfied, resulting in severe inter-symbol interference (ISI). With respect to the CFO, the orthogonality between the two filters protects from performance degradation caused by intercarrier interference (ICI). Numerical results show that FBMCQAM is more robust against CFO while it is more sensitive to TO compared to the FBMC-OQAM system.