AOA Estimation Algorithm Based on Composite and Null Despreaders for Multiple GPS Signals

The Global Positioning System (GPS) is designed to accurately estimate the location information of objects, using signals from at least four GPS satellites. When the high-power interference signals exist, the GPS receiver does not have the proper estimation performance. In this case, we need to enhance the desired GPS signals and to efficiently suppress interference signals. For this purpose, the adaptive beamformer based on the angle-of-arrival (AOA) is widely employed, but the AOA information of the GPS signal is not easily estimated. After conventional despreading, GPS AOA can be estimated using various AOA estimation algorithms such as Multiple Signal Classification (MUSIC), but the estimated result includes not only GPS AOA but also interference AOA at the high-power interference environment. In this paper, we propose a GPS AOA estimation algorithm, based on the composite despreader and the null despreader for multiple GPS signals. The AOA estimation result based on the composite despreading output includes AOAs of GPS and interference signals, and that based on the null despreading output includes only AOAs of interference signals. In order to determine GPS AOAs, we finally compare two results. The proposed algorithm efficiently estimates multiple GPS AOAs at a time, unlike the conventional technique.