Analysis of the performance degradation in uplink MC-CDMA systems with Doppler induced frequency offsets

In this paper, uplink time division duplex (TDD) multi-carrier code-division multiple-access (MC-CDMA) systems applying pre-equalization to combat channel impairments are considered. Especially, the performance degradation caused by the Doppler induced frequency offsets among the different mobile users is analyzed in detail. Based on this analysis different frequency interleaving schemes are proposed and their potential to reduce the performance degradation is investigated. It turns out, that a frequency interleaver which is allowed to skip a few, well-defined subcarriers is capable of reducing the influence of Doppler induced frequency offsets significantly causing a very little loss in bandwidth efficiency.