Deriving AP Position and Antenna Array Orientation for Wi-Fi Localization

Wi-Fi based indoor localization systems leveraging Received Signal Strength Indicator (RSSI) and Channel State Information (CSI) are urgently desirable in recent years due to the ubiquitous deployment of Wi-Fi devices. While CSI based localization systems can realize decimeter-level accuracy, they require a prior knowledge about position and antenna array orientation of Access Point (AP), which makes it challenging for widespread deployment. In this paper, we present a systematical study for CSI indoor localization systems to answer the following question: How to realize decimeter-level localization accuracy without labor-intensive site survey? For this purpose, we propose a novel algorithm to automatically construct the AP layout and then localize mobile devices based on the constructed layout. Furthermore, we present an AP layout revision method to improve the performance of our system. We conduct experiments in different scenarios to verify proposed methods. The results show that we can realize the 80% error within 0.95m, 1.00m, and 0.65m in office room, NLoS and corridor environment respectively which is as accurate as localization systems(SpotFi) with known AP layout.