Blind 2-D RAKE receivers based on RLS-type space-time adaptive filtering for DS-CDMA system

We previously presented a blind 2-D RAKE receiver for CDMA that cancels strong multi-user access interference and optimally combines multipath. The weight vector yielding the optimum signal to interference plus noise ratio for bit decisions is the "largest" generalized eigenvector of the spatio-frequency (spatio-temporal) correlation matrix pencil. However, the eigen-analysis based algorithm is on the order of O(N/sup 3/) computational complexity and the resulting spatio-frequency (spatio-temporal) correlation matrix pencil is of a large dimension. This detracts from the real-time applicability of that scheme. A blind 2-D RAKE receiver is thus presented based on an RLS-type space-time adaptive filtering scheme which offers O(N/sup 2/) computational complexity and competitive performance. The applicability of the scheme to the IS-95 uplink is also addressed as in a decision directed fashion.