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Open AccessArticle

Time-Series Laplacian Semi-Supervised Learning for Indoor Localization

by Jaehyun Yoo
Department of Electrical, Electronic and Control Engineering, Hankyong National University, Anseoung 17579, Korea
This paper is an extended version of our paper published in Yoo, J.; Johansson, K.H. Semi-supervised learning for mobile robot localization using wireless signal strengths. In Proceedings of the 2017 International Conference on Indoor Positioning and Indoor Navigation (IPIN), Sapporo, Japan, 18–21 September 2017.
Sensors 2019, 19(18), 3867;
Received: 10 July 2019 / Revised: 1 September 2019 / Accepted: 5 September 2019 / Published: 7 September 2019
Machine learning-based indoor localization used to suffer from the collection, construction, and maintenance of labeled training databases for practical implementation. Semi-supervised learning methods have been developed as efficient indoor localization methods to reduce use of labeled training data. To boost the efficiency and the accuracy of indoor localization, this paper proposes a new time-series semi-supervised learning algorithm. The key aspect of the developed method, which distinguishes it from conventional semi-supervised algorithms, is the use of unlabeled data. The learning algorithm finds spatio-temporal relationships in the unlabeled data, and pseudolabels are generated to compensate for the lack of labeled training data. In the next step, another balancing-optimization learning algorithm learns a positioning model. The proposed method is evaluated for estimating the location of a smartphone user by using a Wi-Fi received signal strength indicator (RSSI) measurement. The experimental results show that the developed learning algorithm outperforms some existing semi-supervised algorithms according to the variation of the number of training data and access points. Also, the proposed method is discussed in terms of why it gives better performance, by the analysis of the impact of the learning parameters. Moreover, the extended localization scheme in conjunction with a particle filter is executed to include additional information, such as a floor plan. View Full-Text
Keywords: Wi-Fi RSSI-based indoor localization; semi-supervised learning; time-series learning Wi-Fi RSSI-based indoor localization; semi-supervised learning; time-series learning
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Yoo, J. Time-Series Laplacian Semi-Supervised Learning for Indoor Localization. Sensors 2019, 19, 3867.

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