A SINR maximizing RAKE receiver for DS-CDMA downlinks

The RAKE receiver is a matched filter (MF), matched to the operations of spreading, pulse shape filtering and channel filtering. An SINR maximizing linear receiver may perform much better. In the downlink, in which the channel is the same for all intracell signals, and with orthogonal codes and cell-dependent scrambling, good SINR performance can be attained with a RAKE-like receiver. In particular we replace the pulse-shape MF by another filter, and the sparse channel MF by another sparse filter. The first filter is chosen to facilitate the design/adaptation of the sparse filter, the coefficients of which are optimized for maximum SINR. In the presence of intercell interference (other base stations), but using multiple receiver antennas and/or oversampling with respect to the chip rate, good SINR performance can be attained with these structured linear receivers.