WiFi-RTT-SLAM: Simultaneously estimating the positions of mobile devices and WiFi-RTT access points

Abstract

This article aims to explore and extend the research on navigation in indoor environments using smartphones. Using WiFi for indoor positioning is a common approach because WiFi infrastructure is widely deployed. Recently the WiFi IEEE 802.11-2016 standard was released, which includes a fine time measurement (FTM) protocol, more commonly known as WiFi-round-trip-time (WiFi-RTT) protocol, for WiFi ranging. WiFi-RTT enables ranging measurements between a device, i.e. a smartphone, and fixed WiFi-RTT access points (WiFi-RTT-APs). Because the location of WiFi-RTT-APs are typically unknown, this paper presents a novel algorithm which estimates the position of a smartphone together with the location of the WiFi-RTT-APs using a simultaneous localization and mapping (SLAM) method. The derived algorithm is evaluated based on measurements in an indoor environment. We show, that the smartphone and the WiFi-RTT-APs can be localized within meter accuracy, having no prior knowledge about the environment.