Optimal 2D-RAKE receiver for coherent DS-CDMA in multipath

The optimal two-dimension RAKE (2D-RAKE) receiver that permits maximum signal to interference-plus-noise ratio (SINR) is investigated for the cell site of direct sequence code-division multiple access (DS-CDMA) communications with binary phase-shift keying (BPSK) signaling over the correlated Rayleigh multipath fading. The closed-form bit error rate (BER) is derived under the perfect channel estimation and the maximal average SINR is shown to be the overall 2D-diversity order. BER evaluations indicate that, even in correlated fading among antennas, the optimal 2D-RAKE receiver could achieve the maximal 2D-diversity gain from the completely independent multipath components, and a significant capacity advantage over the conventional RAKE or multi-antenna receiver. This performance gain is found to be sensitive to the selection of 2D-weighting vectors and especially the 2D-diversity order