A RAKE structured SINR maximizing mobile receiver for the WCDMA downlink

We propose a RAKE structured receiver with the pulse-shaping MF replaced with another FIR filter, and the sparse propagation channel MF by another sparse filter. We compare different choices for the design of the FIR filter and the sparse filter and their adaptation. We model the channel as an autoregressive first-order process over slot periods, with bandwidth commensurate with the Doppler spread, and we refine the brute pilot-based slot-wise estimate using adaptive causal Wiener filtering across slots. We then apply recursive path extraction in every slot. We also introduce polynomial expansion extensions, one at chip rate to improve the MMSE equalization performance of the structured chip rate equalizer, and one at symbol rate to bring the structured receiver performance closer to that of the global time-varying LMMSE receiver.