Methods for blind equalization and resolution of overlapping echoes of unknown shape

This paper considers the related problems of using an uncalibrated antenna array to (1) recover an unknown signal transmitted over an unknown (but stationary) multipath channel and (2) resolve overlapping pulse echoes with unknown shape. Unlike previously proposed multichannel blind equalization techniques, the methods described herein employ a model based on physical channel parameters rather than unstructured single-input, multi-output FIR filters. The algorithms exploit similarities between a model for the data in the frequency domain and the standard direction-of-arrival estimation problem. This connection between the two problems suggests several different approaches based on, for example, maximum likelihood, MODE, IQML, and ESPRIT. These approaches are developed in some detail, and the results of several simulation examples are included to compare their performance