Blind space-time processor for SINR maximization in CDMA cellular systems

Previously (Ramos and Zoltowski, 1997), we proposed a space-time adaptive RAKE receiver for CDMA that asymptotically provides the optimum combination of space-time samples for maximizing the SINR for the signal with the desired code (SDC) by canceling strong multi-user access interference (MUAI) and optimally combining the multipath. A variation of this 2D RAKE receiver is presented herein yielding a faster convergence rate and lower variance in the output SINR. In contrast to previously proposed techniques, bit synchronization for the SDC is not required. The algorithm presented herein asymptotically provides the exact time of arrivals of the multipaths within a bit period, and subsequently the optimum space-time weights for combining the fingers across both space and time. The instrumental property exploited in this technique is the fact that although the respective spectra of the SDC and MUAI components at the output of the matched filter are statistically equal, the respective spectra of their squared values differ.