Wideband angle of arrival estimation using the SAGE algorithm

In the last few years, issues concerning the spatial resolution of the received electromagnetic field have attracted a lot of attention in mobile communications. A new method for the high resolution of the electromagnetic field with respect to both the incidence direction and delay is presented. The underlying discrete propagation model relies on the assumption that a finite known number of transverse electromagnetic plane waves characterized by their complex amplitude, propagation delay, and azimuthal incidence direction are impinging in a neighborhood of the receiver position. A space-alternating generalized expectation-maximization (SAGE) algorithm is proposed to replace the high-dimensional optimization procedure necessary to compute the joint maximum-likelihood estimate of the waves parameters by several separate maximization processes which can be performed sequentially. The resolution and the mean convergence rate of the scheme are evaluated by means of Monte-Carlo simulations considering discrete synthetic propagation environments. Finally, the applicability of the SAGE algorithm to real propagation environments is demonstrated.