Abstract
The aim of this research is to implement a precise Wi-Fi indoor positioning system (IPS) or localization system based upon the IEEE 802.11mc fine-timing measurement (FTM) scheme also known as the Wi-Fi round trip time (RTT) ranging technique, where ranging refers to a sub-process of positioning that determines the distance between a transmitter and receiver. Our system and its algorithms were implemented using a COTS (Commercial-Off-The-Shelf) smartphone and Wi-Fi access points. Experiments were conducted in several real-life indoor environments. This paper presents the detailed Wi-Fi RTT ranging performance of these devices in different system configurations and characterizes the systematic biases and noise model to improve the ranging accuracy. A novel three-step-positioning method is proposed to overcome the issues of no or multiple intersect points in trilateration due to ranging errors to improve positioning accuracy. This consists of the following: 1) systematic bias determination and removal; 2) clustering-based trilateration (CbT) supported by weighted concentric circle generation (WCCG), namely CbT & WCCG; 3) positioning result and trajectory optimization using a Kalman filter. As a result, the evaluation experiments gave a position accuracy of ±1.2 m in 2D static positioning and ±1.3 m for dynamic motion tracking. Also, our CbT & WCCG method demonstrate good tolerance against ranging errors. Moreover, the computational cost and positioning accuracy of CbT & WCCG methods are compared with least square (LS) and recursive least square (RLS) methods and the accuracy standard deviation of our algorithm is the closest to the Cramer–Rao bound (CRB).
Highlights
Indoor Positioning Systems (IPS) are increasingly needed communication can be used for positioning – a Wi-Fias we spend more time indoors based positioning system (WPS), which is the focus of this and as indoor spaces become far more complex
Because we only present the positioning performance in a 2D plane, the MT and Access Point (AP) are placed at the same altitude, 1.4 m from the floor
We proposed a new systematic bias removal process and proved that it significantly improves the ranging accuracy and the positioning accuracy when Wi-Fi Round-Trip Time (RTT) is implemented as an indoor positioning system
Summary
Indoor Positioning Systems (IPS) are increasingly needed communication can be used for positioning – a Wi-Fias we spend more time indoors (at least in urban areas) based positioning system (WPS), which is the focus of this and as indoor spaces become far more complex. There known as a fingerprinting-based technique [3][4] which is are no global maps, indoor spaces often tend to be generally considered to be more accurate than the path loss more 3D rather than 2D and furniture and objects are often model based method [5]. This method typically includes moved around changing the free path for navigation
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