Optimization of FBMC Waveform by Designing NPR Prototype Filter with Improved Stopband Suppression

FBMC can relax the out-of-band emissions problem in OFDM by using well-designed prototype filter such as the isotropic orthogonal transform algorithm. In order to achieve more flexibility in filter performances as well as to improve FBMC frequency selectivity, this paper puts forward a design method of nearly perfect reconstruction (NPR) prototype filter, in which the Nyquist condition can be constrained by using the filter autocorrelation coefficients. Then, we can apply the spectral factorization to retrieve the final prototype filter, and the filter results show advantages over conventional ones in terms of sidelobe suppression, especially in the region near the transition band. Such advantages finally result in bit-error-rate (BER) superiority in FBMC simulations, which definitely confirms the effectiveness of the proposed design method for NPR prototype filter.