IEEE 802.11 Wi-Fi access point localization with angular signal strength information

A better understanding of the spatial structure of existing opportunistic wireless network deployments will offer new insights for future deployments, e.g. dense femtocell networks. In this paper we present a performance analysis for three different localization algorithms that support such efforts by finding the location of IEEE 802.11 Wi-Fi access points (APs) from distributed signal strength measurements. These algorithms extend prior works on omnidirectional single-point measurements and includes angular information into the estimation process. Using a custom-made measurement setup, we have collected data for typical indoor and outdoor scenarios which are likely to be encountered in large measurement campaigns. We quantify and reason on the localization error for each scenario and algorithm, and propose a weight spread estimate for determining the robustness of the localization approaches. Through variations in the used sample data set we further discuss relevant observations on the stability of the different algorithmic estimation approaches. Our results show that overall propagation-centric algorithms perform best, but that algorithms that build a stochastic model of angular signal strength distribution are more robust if only few measurements are available.