An MMSE-EIC equalization for FBMC/OQAM systems

Abstract

Filter bank multicarrier/offset quadrature amplitude modulation (FBMC/OQAM) is one of a promising transmission technique of the fifth generation (5G) system. By using a pulse shape with good time frequency localization (TFL), it removes cyclic prefix (CP) to obtain a higher spectral efficiency and lower out-of band radiation compared with orthogonal frequency division multiplexing (CP-OFDM). However, non-orthogonal filters in transmitter and receiver bring interferences between adjacent symbols and carriers, which ask for a more efficient way to demodulate the data from receiver other than a simple 1-tap Zero Forcing (ZF) method. Among various equalizers proposed in recent years, a new equalization with Interference Cancellation (EIC) shows its good performance and appropriate complexity in cancelling the intrinsic inter-carrier/inter-symbol interference. In this paper, we present minimum mean square error (MMSE) algorithm to apply the EIC equalizer. Since the usual ZF has the performance floor in FBMC/OQAM system, MMSE equalization gains a better effect. We first analyze the principle of the system, then derive a close-form of this modified MMSE-EIC equalization. Finally, simulation results demonstrate that the developed equalizer outperforms the ZF and MMSE equalizer in the case of multipath fading channels in terms of bit error rate (BER).