Subspace-based adaptive multiuser interference cancellation for CDMA system

We combine the adaptive MMSE detector which employs an antenna array with interference cancellation in a multistage detection scheme. The proposed detectors are based on the signal subspace estimation. The dimension of the latter is decreased each time an interferer is removed from the received signal. The orthonormal projection approximation subspace tracking (OPAST) is used to adaptively estimate the proposed detectors and the spatial signatures. Compared with the MMSE detector, the resulting detectors offer a superior performance in terms of the BER.