Comparing Effects of Carrier Frequency Offset on Generalized Multi-Carrier and OFDM Systems

The carrier frequency offset (CFO) could destroy the orthogonality of OFDM subcarriers and induce the inter-carrier interference (ICI) spread. However, the generalized multi-carrier (GMC) system reflects different interference characters in the presence of CFO. In this paper, we exactly analyze the CFO effect on GMC, which multiplexes several single band single carrier based frequency division multiple access (SC-FDMA) streams in frequency domain, under the scenario of additive white Gaussian noise (AWGN) channels. A closed-form expression of signal to interference plus noise ratio (SINR) is derived for the GMC systems in the presence of CFO. Furthermore, the bit error rate (BER) performance analysis is also performed in comparison with the traditional OFDM system for both uncoded and coded environments. Analysis and simulation results show that the feature procedure of discrete Fourier transform (DFT) spread may condense the CFO-induced interference in the first symbol of each subband, resulting in less interference in other symbols. Such condensing procedure can provide robustness against the CFO effect, which also lies on the subband bandwidth for GMC systems. In contrast to the conventional OFDM system, GMC exhibits more robustness when each subband width is designed for 4 times larger than the subcarrier spacing.