Performance of OFDM systems with time-limited waveforms over multipath radio channels

Pulse shaping can effectively reduce the sensitivity of orthogonal frequency division multiplexing (OFDM) scheme to frequency and time variations but at the same time introduce correlation between subcarriers that destroys the orthogonality of the system. This correlation is however well defined and can be effectively used at the receiver in the detection process. This paper investigates the performance of OFDM systems when using time-limited waveforms over multipath radio channels. For pulse shaping of the same duration as the OFDM block interval, the memory between the subcarriers can be fully utilized by means of a maximum likelihood sequence estimation (MLSE) detector. It is shown that with such a detector, pulse shaping improve the performance of OFDM systems in multipath radio channels. The obtained results also show the advantage of employing pulse shaping with OFDM systems in the presence of long echoes.