Optimizing the performance of limited complexity RAKE receivers

Channel estimation is critical to coherent RAKE receiver performance. We investigate maximum likelihood (ML) channel estimation with side information, using knowledge of the transmit and receive filter responses. Such an approach accounts for the interaction between multipath components. For delay estimation, the ML approach optimizes the RAKE finger placement, even when there are an insufficient number of RAKE fingers. For channel coefficient estimation, the ML approach optimizes combining, regardless of the delay estimation approach used. Suboptimal approaches are also developed, which reduce the complexity at a slight cost in performance