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Optimization-Based Wi-Fi Radio Map Construction for Indoor Positioning Using Only Smart Phones.

Jian Tan^1,2, Xiangtao Fan^3,4, Shenghua Wang⁵

¹Hainan Key Laboratory of Earth Observation, Sanya 572029, China. tanjian@radi.ac.cn.

Sensors (Basel, Switzerland)

|September 19, 2018

Summary

This study introduces a smartphone-based method for easy Wi-Fi indoor positioning site surveys. It significantly reduces the labor involved in creating radio maps, achieving accurate results without extra hardware.

Keywords:

Wi-Fi indoor positioning factor graph optimization pedestrian dead reckoning radio map

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Area of Science:

Computer Science
Electrical Engineering
Geomatics Engineering

Background:

Wi-Fi fingerprinting is crucial for indoor positioning where GPS is unavailable.
Traditional site surveys for creating radio maps are labor-intensive and require specialized hardware.
Efficient radio map generation is essential for accurate Wi-Fi based localization.

Purpose of the Study:

To propose a novel, hardware-free method for simplifying the site survey process in Wi-Fi indoor positioning.
To enable users to generate accurate radio maps using only a smartphone.
To validate the proposed method's effectiveness and the quality of the generated radio map.

Main Methods:

Utilizes smartphone-collected inertial sensor data for pedestrian dead-reckoning to generate an initial trajectory.
Employs factor graph optimization to refine the trajectory using Wi-Fi fingerprints and landmark constraints.
Validates the generated radio map using the k-Nearest Neighbor (kNN) algorithm.

Main Results:

The proposed method allows site surveys using only a smartphone, eliminating the need for extra hardware.
Achieved a mean positioning error of 1.10 m and a maximum error of 2.25 m in experimental validation.
The generated radio map demonstrated sufficient accuracy for indoor positioning applications.

Conclusions:

The developed method significantly simplifies the labor-intensive site survey process for Wi-Fi indoor positioning.
Smartphone-based data collection combined with factor graph optimization offers an efficient approach to radio map creation.
The results confirm the feasibility and accuracy of the proposed technique for practical indoor localization systems.