A Comparison between Coded OFDM/OQAM and CP-OFDM Modulations over Multipath Channels

Power Line Communications (PLC) are usually subject to severe degradations, partly due to the channel time dispersion. OFDM is a widely used multicarrier modulation scheme (MCM) for such frequency selective channels, because of the simplicity of the required equalization, and also because of its robustness toward Inter Symbol Interference (ISI), thanks to Cyclic Prefix (CP) insertion. However, other MCM schemes such as OFDM/OQAMcan sometimes be preferred to OFDM, for specific reasons, e.g. time or frequency localization. But, unlike CP-OFDM, OFDM/OQAM exhibits extra ISI and Inter-Carrier Interference (ICI) terms. This paper provides a comparison between both modulation schemes, including coding, for transmission cases where these interference terms cannot be neglected. An accurate Log-Likelihood Ratio calculation is derived for OFDM/OQAM in the case of a transmission through a PLC channel being also impaired by an impulsive noise. Simulation results are reported for a double binary turbo code considering two different block lengths.