Joint angle and delay estimation for DS-CDMA with application to reduced dimension space-time RAKE receivers

In this paper, we propose an algorithm for joint estimation of the angle of arrival (AOA) and delay of each dominant multipath for the desired user for use in a reduced dimension space-time RAKE receiver for DS-CDMA communications that is "near-far" resistant. After we estimate the desired spatio-frequency signal vector, we propose the 2D unitary ESPRIT algorithm as our estimator which provides closed-form as well as automatically paired AOA-delay estimates. We effectively have a single snapshot of 2D data and thus require 2D smoothing for extracting multiple snapshots. The comparative performance of two 2D smoothing schemes, pre-eigenanalysis and post-eigenanalysis 2D smoothing, is discussed. The space-time data model for the IS-95 uplink is presented. The performance of a reduced dimension space-time RAKE receiver for the IS-95 uplink using the AOA-delay estimates is assessed through Monte-Carlo simulations.