Reduced-rank adaptive MMSE equalization for the forward link in high-speed CDMA

Abstract

The chip-level MMSE estimate of the (multi-user) synchronous sum signal transmitted by the base-station, followed by a correlate and sum, has been shown to perform very well in the CDMA forward link using orthogonal channel codes. In this paper, adaptive reduced-rank, chip-level MMSE estimation based on the Multi-Stage Nested Wiener Filter (MSNWF) is presented. Our simulations show that, adaptive MSNWF operating in a very low rank subspace and using the pilot channel for training can achieve near full-rank performance at a fast convergence speed.