Waveform optimization of BFDM for massive connections support over dispersive channels

This paper presents a bi-orthogonal waveform optimization for frequency division multiplexing signaling to support massive connections feature in Internet-of-Things (IoT). Increasing the number of subcarriers within a narrow bandwidth helps to support massive connections in the system. In this paper, we try to optimize the bi-orthogonal pulse shaping to reduce inter-symbol interference (ISI) and inter-carrier interference (ICI) for Bi-orthogonal Frequency Division Multiplexing (BFDM) in a mobile environment. We apply B-splines and Gaussian pulses with the canonical Gabor tight window to calculate receive pulses. In particular, the pulse in BFDM is optimized by minimizing the tail of the ambiguity function to reduce ISI and ICI. The numerical simulation is provided to evaluate the signal-to-interference ratio (SIR) and the number of supporting subcarriers in doubly dispersive channels. The simulation shows that the bi-orthogonal pulse shape optimization in BFDM helps to reduce the ISI/ICI so that the number of supporting subcarriers within a fixed bandwidth can be increased by around two orders of magnitude.