Pre-Compensation of Fading Channels for Uplink Time Division Duplex MC-CDMA Systems
I. Cosovic, Michael Schnell, Andreas Springer · elib (German Aerospace Center) · 2003
Abstract — Time division duplex multi-carrier code-division multiple-access (TDD/MC-CDMA) exploits the strong correlation between up- and downlink channel conditions of the slowly timevarying channels. The TDD mode enables pre-compensation of the channel influence on the uplink signal already at the mobile station based on the channel estimation from the downlink signal. The aim of this paper is to carry out a performance comparison of different TDD/MC-CDMA channel pre-compensation techniques in the uplink and to evaluate the limitations of applicability of TDD/MC-CDMA due to the time variations of the channel. Furthermore, the power constraint condition, that keeps the transmitted power the same as in the case without pre-compensation, is introduced. Different pre-compensation techniques with power constraint are investigated in different mobile radio environments and for different lengths of the transmission frame. I.