Analysis of the Optical OFDM/OQAM Systems with the Using of IOTA Filter

Compared with the conventional orthogonal frequency division multiplexing (OFDM) system, the orthogonal condition of the orthogonal frequency division multiplexing with offset quadrature amplitude modulation (OFDM/OQAM) system only holds in the real field. Due to the relaxation of the orthogonal condition, OFDM/OQAM systems could remove cyclic prefix (CP) and obtain higher net bit rate. However, for OFDM/OQAM systems, the intrinsic imaginary interference (IMI) seriously deteriorated the system performance. In order to combat IMI, the prototype filter with well time frequency Iocalization (TFL) property is highly desired for OFDM/OQAM system. In this paper, we analyzed the IMI in the optical OFDM/OQAM system, and discussed the TFL property of the filter bank for this kind of system. Then we compared the performance of the optical OFDM/OQAM system with the using of the isotropic orthogonal transform algorithm (IOTA) filter, square root raised cosine (SRRC) filter and extended Gaussian function (EGF) filter respectively. As demonstrated in the TFL property analysis and simulation results, the system robustness against IMI can be improved significantly by the using of the IOTA filter thanks to the optimal TFL property.