Direction-of-Arrival Estimation using High-Altitude Platform

High-Altitude Platform (HAP) is a promising technique for providing wireless communications services with improved performance compared to terrestrial and satellite systems. A critical issue in this emerging system is the difficulty of providing user location information through two-dimensional direction-of-arrival (2D-DOA) estimation due to the high computational complexity and the large covered area. Therefore, in this book, efficient techniques have been introduced to determine user location through 2D-DOA with a reduced processing time. Two techniques are demonstrated where the first is based on vertical uniform linear array located perpendicularly at the center of another uniform circular array. The second technique estimates the 2D-DOA in two stages; the first will utilize a low-resolution 2D-DOA estimation technique such as Bartlett algorithm performed on a low-resolution distance grid, then applying a suitable threshold on the normalized Bartlett 2D-DOA spectrum to define ground windows for the next high-resolution 2D-DOA stage.