Robust positioning systems in the presence of outliers under weak GPS signal conditions

In this paper, two epoch-by-epoch robust positioning techniques for global positioning system (GPS) are proposed to deal with the problem of positioning in weak signal conditions in which the probability of outlier in signal acquisition is larger than zero. We propose to accept outliers into the positioning algorithm, however, in this case either robust estimation or outlier detection must be used to overcome the devastating effect of such outliers on traditional positioning algorithms. In order to improve the sensitivity of a GPS receiver, we propose to use novel methods that are able to deal with the problem of estimating the position of a receiver based on pseudo-ranging measurements that are contaminated by outliers. Simulations are carried out to demonstrate the robustness of the proposed techniques in terms of success rate of the algorithms in finding the correct solution, when there are a different number of outliers in ranging measurements from satellites.