CRB analysis of planar antenna arrays for optimizing near-field source localization

This paper focuses on the Cramer Rao bound (CRB) of the azimuth, elevation and range with planar arrays for narrowband near-field source localization, using the exact expression of the time delay. Specifically, the aim of this paper is twofold. First, we derive explicit non-matrix closed-form expressions of approximations of these three CRBs. Second, we use these expressions to optimize near-field source localization. For deriving these expressions, we introduce conditions on the array geometry that allow us to decouple the azimuth, elevation and range parameters to a certain order in lambda/r (in which lambda and r denote the wavelength and the range, respectively). A particular attention is given to the popular array configurations which are the concentric uniform circular-based arrays, cross and square-based centro-symmetric arrays which satisfy these conditions. In order to control directions of arrivals (DOA) ambiguity, we propose a new criterion, which allows us to design non-uniform square [resp., cross] -based centro-symmetric array configurations with improved near-field range estimation capabilities without deteriorating the DOA precisions w.r.t uniform square [resp., cross] -based arrays. Finally, we specify the accuracy of our proposed approximated CRBs' expressions and isotropy's conditions w.r.t. the range and the number of sensors. (C) 2016 Elsevier B.V. All rights reserved.