Blind time delay estimation in asynchronous CDMA via subspace intersection and ESPRIT

The implementation of a RAKE receiver for a quasi-synchronous DS-CDMA (direct sequence code division multiple access) system requires the estimation of the dominant path delays for each user. We present a blind method to estimate these parameters. The algorithm takes advantage of various signal space invariances in the frequency domain to isolate the subspace of interest for each user, then uses ESPRIT on these subspaces to estimate the delays. The method processes each user independently of the others, is near-far resistant, and allows several delays per user. Simulations indicate a fair accuracy