Iterative channel estimation for multiuser OFDM systems in the presence of power amplifier nonlinearities,

FERNANDO GREGORIO; STEFAN WERNER; JUAN COUSSEAU; TIMO LAAKSO

Helsinki

Conferencia; 17th Annual IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC 2006,; 2006

Helsinki University of Technology, Signal Processing Laboratory

This paper proposes a new channel estimation approach forMIMO-OFDM systems subject to power amplifier nonlinearities.The harmful effect of nonlinear distortion on the systemperformance can be reduced by applying an iterative distortioncancellation technique. However, such an approach requiresaccurate channel estimates to yield good performance. In ourapproach, initial channel estimation is carried out in frequencydomain (FD) followed by time domain (TD) processing of thereceived signal. In the TD step, the equalized signals fromthe FD processing is used to remove the nonlinear distortionand to improve the initial channel estimate. Simulations verifythat the combined channel estimation and nonlinear cancellationstrategy has a performance close to the case of perfectlyknown channel. Furthermore, a substantial improvement in thesystem performance is achieved with the proposed techniquewhen compared with conventional methods in terms of meansquare error and BER.