System capacity of wideband OFDM communications over fading channels without channel knowledge

Assuming PSK modulation, we derive the system capacity of pulse-shaped orthogonal frequency division multiplexing (OFDM) communications over time-frequency selective fading channels in the absence of channel state information at the transmitter and the receiver. We show that capacity tends to zero in the large bandwidth limit and quantify the impact of spread and shape of the scattering function on finite bandwidth capacity