Filter optimization of out-of-band emission and BER analysis for FBMC-OQAM system in 5G

Filter optimization of out-of-band emission plays an important role for FBMC-OQAM system. The main idea of this paper is to minimize the stopband energy with constraints of sidelobe and interchannel interference (ICI)/intersymbol interference (ISI) by optimizing the filter coefficients. The main contribution is that the improved approach reduces the stopband energy and suppresses the sidelobe simultaneously with nearly perfect reconstruction (NPR) condition. Simulation results show that the improved filter reduces the stopband energy and the sidelobe more than the optimized windowing based filter. Meanwhile, the improved filter has almost the same bit error rate (BER) performance as the optimized windowing based filter for FBMC-OQAM system in additive white Gaussian noise (AWGN) channel.

I. Introduction

Orthogonal frequency division multiplexing (OFDM) has been widely applied in broadband multicarrier communications. However, it has some shortcomings, such as high leakage, stringent orthogonality of overall subcarriers. To make up for the shortcomings of OFDM system, many researchers focus on the filter bank multicarrier (FBMC) modulation recently [1]. FMBC technique whose subcarrier does not need orthogonality and cyclic prefix (CP) insertion, has flexible resource allocation, dynamic selection and configuration of the waveform formats according to the different application scenarios. Furthermore, it brings advantages such as lower sidelobe and robustness to narrow band interference [2]. We note that most of the advantages of FBMC originate from the fact that, by design, the nonadjacent subcarriers in this modulation are separated almost perfectly through a bank of well-designed filters. The waveform of the fifth generation (5G) mobile communication system should be able to solve scenarios with asynchronous and non-orthogonality. So, FBMC technique may be used in the next generation wireless communication system [3].