Fast converging PE detectors with good near-far resistance in UTRA FDD uplink

The polynomial expansion (PE) multiuser detector (MUD) has been suggested as an iterative approach that approximates the decorrelating and minimum mean-squared error (MMSE) MUDs. By using a series expansion rather than a matrix inversion, the complexity of the PE MUD can be O(K²) rather than O(K³). Firstly, the text at hand repeats different estimation methods for the eigenvalues of the correlation matrix covering the transmission. The eigenvalues have to be estimated tightly, for they are responsible for both assuring convergence and improving convergence speed of the iteration. Thus, a tight estimation of the eigenvalues results in a faster convergence of the PE detector to the decorrelating or the MMSE detector. In this article, we observe the near-far resistance. In addition, the influence of the estimated eigenvalues on the BER and near-far resistance is evaluated. The PE detectors are tested in an UMTS terrestrial radio access (UTRA) frequency division duplex (FDD) uplink multiuser environment with totally asynchronous users.