Channel estimation for downlink UMTS RAKE receivers

This paper presents a decision-aided-decision-directed approach to estimate the channel coefficients for the RAKE receiver in the UMTS context. The algorithm developed gently adapts is behavior to properly deal with static channels and fast varying channels. Closed form equations will be derived to update the channel coefficients estimates symbol wise without any matrix inversion, using only vector and matrix products. The algorithm performance is evaluated against a decision directed (DD) and a decision aided (DA) channel estimators used in a RAKE receiver. The experiments show the good behavior of the proposed algorithm.