MMSE equalizers for multitone systems without guard time

Recently the concept of multitone modulation or OFDM has received much attention. For such a modulation, the dispersiveness of the channel is classically solved by the technique of guard time. In the present paper we investigate the performance of OFDM without guard time but with MIMO equalization. Linear and decision-feedback structures structures are derived for an MMSE criterion and their performance is assessed by means of their steady-state behavior. Symbol rate equalizers following channel matched filters are derived and investigated. It is shown that equalized OFDM outperforms OFDM with guard time.