Filtered-OFDM for High-speed Railway Communications

The challenge of deploying orthogonal frequency division multiplexing (OFDM) for high-speed railways (HSRs) is associated with its high mobility and delay spread. These two conditions introduce loss of orthogonality between the OFDM subcarriers, hence, degrades the system performance. Although OFDM can provide high spectrum efficiency, but due to its inherited rectangular pulse shape, the frequency spectrum produced is not very well localized, which blocks its coexistence with other systems in adjacent carriers. Compared to the conventional OFDM, filtered OFDM (f-OFDM) has a lower out-of-band (OOB) interference and spectrum leakage. Therefore, f-OFDM is attractive to be implemented in high mobility applications such as in HSR, as considered here. By using the Hann and root-raised cosine (RRC) filters, simulation results show that f-OFDM provides better bit error rate (BER) and reduced OOB emission compare to conventional OFDM.