Multicarrier Waveform Processing for HF Communications

High-frequency (HF) band communications can be flexibly realized using multicarrier modulation (MCM) techniques. HF channels are typically characterized by severe multi-path effects and high Doppler spreads requiring advanced estimation and equalization methods as well as elaborate waveform design for addressing these issues. This paper compares the performance of three widely utilized MCM techniques, namely, cyclic prefix (CP) orthogonal frequency-division multiplexing (OFDM), filter bank multicarrier/offset-QAM (FBMC/OQAM), and filtered multitone (FMT) in HF communications. In addition, the filtered variant of CP-OFDM is included in the comparison. The performance of these systems is simulated using commonly adopted HF-channel models. Channel estimation is carried out using scattered pilots with minimum mean-squared error based interpolation schemes whereas the equalization is realized using frequency-sampling based subcarrier equalizer. It is shown that the simulated uncoded bit-error rate of CP-OFDM is superior when compared with FBMC/OQAM and FMT even in the case when CP-OFDM waveform is filtered for better spectral containment. In addition, the implementation complexity and peak-to-average power ratio performance of (filtered) CP-OFDM compare favourable with FBMC/OQAM and FMT.