Optimum Pulse Shaping for OFDM/BFDM Systems Operating in Time Varying Multi-Path Channels

In this paper, we consider a pulse shaping OFDM/BFDM system operating over a doubly dispersive channel. We propose to search the optimal pulse maximizing the signal to interference ratio (SIR). We show that the impact of interference, composed by both inter-symbol interference (ISI) and inter-carrier interference (ICI), occurring in such a system, depends crucially on time frequency localization of transmit and receive pulses. We propose to maximize the SIR, written as a ratio of two quaternary forms, by altering between transmit and receive pulse spaces both generated by Hermite Waveforms. Numerical results show that optimized BFDM systems can outperform conventional OFDM systems with respect to SIR. In fact, biorthogonality offers more freedom to design pulses improving robustness of the multi-carrier system against channel dispersion.