Filter Optimization for MFTN-OQAM Systems

Abstract

In this paper, a novel and effective method for designing the pulse shaping filter for multicarrier faster-than-Nyquist with offset quadrature amplitude modulation (MFTN-OQAM) systems is proposed. The connection between the signal-to-interference ratio (SIR) and the filter coefficients is first established. Then, for a desired overall compression level taking into account compressions in both frequency and time domains, a simple convergence search is suggested to jointly find the optimal values of time and frequency compression factors as well as the filter coefficients to maximize the SIR under a spectrum localization constraint. The obtained results show that higher SIRs, and consequently better bit error rates, can be achieved by the proposed filters over the Martin filter that is commonly used in the filter-bank multicarrier OQAM (FBMC-OQAM) systems (i.e., without time or frequency compression). Moreover, when applying our method to FBMC-OQAM systems, the obtained results show that the original Martin filter is suboptimal as shorter filters are found having the same SIR, which translates to lower implementation cost and latency.

Keywords

• Faster-than-Nyquist signaling
• FBMC
• multicarrier faster-than-Nyquist (MFTN)
• OFDM
• offset QAM (OQAM)