Enhancements of unitary esprit for non-circular sources

Subspace based high-resolution parameter estimation algorithms often use forward-backward averaging to enhance their resolution, especially in case of correlated sources. Further enhancements can be achieved if the source signals are non-circular. In this paper, we derive an efficient subspace estimation scheme that exploits the non-circularity of the sources and already includes forward-backward averaging. Moreover, appropriate spatial smoothing techniques are introduced. Completely real-valued implementations of 1-D and 2-D Unitary ESPRIT for non-circular sources are presented as examples. In these cases, NC Unitary ESPRIT improves the resolution capability and the noise robustness of standard ESPRIT as well as Unitary ESPRIT and can handle more sources than sensors.