Multi-carrier modulation schemes for frequency-selective fading channels

The performance of orthogonal frequency division multiplexing (OFDM) modulation schemes using differential (DPSK-OFDM), coherent (PSK-OFDM) data modulation and multi-carrier code division multiple access (MC-CDMA) are compared for time-variant and time-invariant multipath channels. Ignoring the CDMA aspect, MC-CDMA can be viewed as a novel modulation technique. While coherent OFDM and MC-CDMA require channel equalization, differential OFDM can work without it. As a channel equalization method a new controlled equalization scheme is introduced and investigated by simulations. MC-CDMA with controlled equalization is shown to be the most suited multi-carrier modulation principle over time-variant and time-invariant frequency-selective channels.