Soft-decisions in multistage RAKE receiver in 3GPP implementation

This paper proposes a new two-stage reconstructive RAKE receiver for the mobile station with the objective to improve the BER performance. The proposed receiver will be compliant with the specifications issued by the 3rd Generation Partnership Project (3GPP). Using channel estimates derived from a least-squares algorithm based on the prior knowledge of the pilot bits, soft-decisions are made on the received signal. These soft-decisions are used to identify the weaker bits from the stronger ones, so that we may subsequently reconstruct a signal based on these stronger bits and remove this reconstructed signal from the original received signal. This effectively removes self-interference (as a result of the multipaths) in the second stage of RAKE processing. Simulations are carried out over a fast-fading mobile channel model, and results are indicative of an improved performance. Specifically, the receiver is able to achieve a performance as if there is one less interfering user as compared to the conventional receiver.