A fast converging polynomial expansion multiuser detector applied to UTRA FDD uplink

The polynomial expansion (PE) multiuser detector (MUD) is a well known iterative approach to approximate the decorrelation or the minimum mean-squared error (MMSE) detectors. The computational complexity for the direct matrix inversion involved with the decorrelation and the MMSE detector is O(K³). Due to the iterative approximation, the computational complexity of the PE detector can be O(K²) instead of O(K³). The text at hand compares the different estimation methods for the eigenvalues of the correlation matrix covering the transmission. As demonstrated, the tight estimation of the eigenvalues utilized here results in a faster convergence of the decorrelation or the MMSE detector. As an application, the PE detectors presented here are tested in an UMTS terrestrial radio access (UTRA) frequency division duplex (FDD) uplink multiuser environment, where the multiple users are assumed to be totally asynchronous.