FrFT-based EO-STBC multicarrier system for transmission over doubly-dispersive channels

This paper focuses on the enhancement of extended orthogonal space-time block coding (EO-STBC) when transmitting over a doubly-dispersive channel. The frequency selective nature of the channel favours the combination with a multicarrier approach such as orthogonal frequency division multiplexing (OFDM). However, as Doppler spread increases, OFDM loses its orthogonality, resulting in severe inter-symbol (ISI) and inter-carrier interference (ICI). This is addressed firstly by the generalisation of OFDM to fractional Fourier transform (FrFT)-based multicarrier approaches, which can provide better resilience in the presence of Doppler spread. Secondly, in higher mobility scenarios, an equalisation scheme is employed, whose lower complexity in an FrFT-based multicarrier setting can further minimised by a reduction of the equaliser. Simulation results highlighting the potential performance improvements are presented.