WILS: Wireless Indoor Localization System using Commercial WiFi Infrastructures with Decimeter Accuracy (original) (raw)

2017, Proceedings of the 3rd International Conference on Wireless Communication and Sensor Networks (WCSN 2016)

we present Wireless Indoor Localization System (WILS) that enables commercial WiFi infrastructures to implement localization in the complex indoor environment. Receive Signal Strength Indication (RSSI) is utilized by some systems to get a high accuracy of localization, but they are easily be affected by the environment. Other use modified hardware or firmware, such as increasing the number of antennas to obtain enormous location precision. To solve this problem, WILS uses physical layer information, called Channel State Information (CSI). And it does not require modification in any hardware and firmware. WILS makes four technical contributions for achieving a high accuracy in localization. At first, it proposes a new algorithm, called Modified MUSIC (M-MUSIC), and it can estimate Angle of Arrival (AoA) and Time of Flight (ToF) at the same time from CSI information. Next, it introduces some methods to sanitize the phase, and improve the accuracy of measured phase. Third, it presents an idea of window slides to do CSI Smoothing for CSI measurements. Finally, it utilizes clustering algorithm to identify Line of Sight (LoS) path, and combines the AoA for LoS path and RSSI to locate the target. Our implementation on commodity WiFi cards demonstrates that WILS's accuracy is comparable to advanced localization systems, it can achieve a median accuracy of 60 cm. Keywords-indoor localization; channel state information (CSI); angle of arrival (AoA); time of flight (ToF); modified MUSIC, line of sight(LoS); phase sanitization I.