Analysis of multicarrier transmission in time-varying channels

Transceiver design is dependent on the a priori information available about the communication environment. We consider two cases: channel completely known at the receiver and transmitter (via feedback); and only channel statistics are known at the transmitter and the channel is known at the receiver. We develop an information-theoretic analysis of these scenarios by examining the mutual information expressions. We analyze a vector coding scheme suitable for time-varying channels and illustrate its asymptotic optimality. We examine the expected mutual information for slowly fading channels and investigate the OFDM transceiver structure. We then derive the average mutual information for OFDM in time-varying environments. This allows us to study the effect of time-variation on OFDM packet-size design. We illustrate the transmission overhead requirements through a numerical example