Pre-Compensation of Fading Channels for UplinkTime Division Duplex MC-CDMA Systems

摘要

Time division duplex multi-carrier code-divisionmultiple-access (TDD/MC-CDMA) exploits the strong correlationbetween up- and downlink channel conditions of the slowly timevaryingchannels. The TDD mode enables pre-compensation ofthe channel influence on the uplink signal already at the mobilestation based on the channel estimation from the downlink signal.The aim of this paper is to carry out a performance comparison ofdifferent TDD/MC-CDMA channel pre-compensation techniquesin the uplink and to evaluate the limitations of applicability ofTDD/MC-CDMA due to the time variations of the channel. Furthermore,the power constraint condition, that keeps the transmittedpower the same as in the case without pre-compensation,is introduced. Different pre-compensation techniques with powerconstraint are investigated in different mobile radio environmentsand for different lengths of the transmission frame.