Space–time adaptive reduced-rank processor for interference mitigation in DS-CDMA systems
Rodrigo C. de Lamare, Raimundo Sampaio‐Neto · IET Communications · 2008
A space–time adaptive reduced-rank processor for interference mitigation in DS-CDMA systems is proposed based on interpolated finite impulse response filters with time-varying interpolators. The proposed space–time processor allows a significant reduction in the number of estimation elements, thereby increasing the convergence and tracking performance of the estimation algorithms. In order to compute the parameters of the proposed space–time processor, a least squares design is presented and computationally efficient recursive least-squares (RLS) algorithms are developed for estimating the parameters of both reduced-rank receiver and interpolator. A linear and successive interference cancellation space–time receivers based on the proposed reduced-rank processor for mitigating multi-access and intersymbol interference in an uplink scenario are proposed. An analysis of the convergence properties of the proposed space–time processor is carried out and analytical expressions are derived for predicting the mean squared error performance of the proposed RLS algorithm. Simulation results show that the proposed reduced-rank space–time processor and RLS algorithms outperform existing techniques at lower complexity.