The development of indoor positioning solutions using smartphones is a growing activity with an enormous potential for everyday life and professional applications. The research activities on this topic concentrate on the development of new positioning solutions that are tested in specific environments under their own evaluation metrics. To explore the real positioning quality of smartphone-based solutions and their capabilities for seamlessly adapting to different scenarios, it is needed to find fair evaluation frameworks. The design of competitions using extensive pre-recorded datasets is a valid way to generate open data for comparing the different solutions created by research teams. In this paper, we discuss the details of the 2017 IPIN indoor localization competition, the different datasets created, the teams participating in the event, and the results they obtained. We compare these results with other competition-based approaches (Microsoft and Perf-loc) and on-line evaluation web sites. The lessons learned by organising these competitions and the benefits for the community are addressed along the paper. Our analysis paves the way for future developments on the standardization of evaluations and for creating a widely-adopted benchmark strategy for researchers and companies in the field.
The Indoor Positioning and Indoor Navigation (IPIN) conference holds an annual competition in which indoor localization systems from different research groups worldwide are evaluated empirically. The objective of this competition is to establish a systematic evaluation methodology with rigorous metrics both for real-time (on-site) and post-processing (off-site) situations, in a realistic environment unfamiliar to the prototype developers. For the IPIN 2018 conference, this competition was held on September 22nd, 2018, in Atlantis, a large shopping mall in Nantes (France). Four competition tracks (two on-site and two off-site) were designed. They consisted of several 1 km routes traversing several floors of the mall. Along these paths, 180 points were topographically surveyed with a 10 cm accuracy, to serve as ground truth landmarks, combining theodolite measurements, differential global navigation satellite system (GNSS) and 3D scanner systems. 34 teams effectively competed. The accuracy score corresponds to the third quartile (75 th percentile) of an error metric that combines the horizontal positioning error and the floor detection. The best results for the on-site tracks showed an accuracy score of 11.70 m (Track 1) and 5.50 m (Track 2), while the best results for the off-site tracks showed an accuracy score of 0.90 m (Track 3) and 1.30 m (Track 4). These results showed that it is possible to obtain high accuracy indoor positioning solutions in large, realistic environments using wearable light-weight sensors without deploying any beacon. This paper describes the organization work of the tracks, analyzes the methodology used to quantify the results, reviews the lessons learned from the competition and discusses its future.
This paper presents a novel iterative receiver used to mitigate the impact of impulsive noise (IN) on orthogonal frequency division multiplexing (OFDM) based baseband powerline communications. An adaptive threshold is mathematically derived for the detection of IN under a desired false alarm probability. This detection mechanism is then used to mitigate IN in two stages. Prior to the OFDM demodulation, a pre-IN mitigation block is used to clip the stronger portions of the IN source. This pre-processing significantly reduces the power of the IN spreading into all subcarriers and thus facilitates the detection of residual IN in the second stage. After the OFDM demodulation, the proposed receiver iteratively estimates the channel impulse response and reduces IN sources that were not detected by the pre-IN mitigation block. Post-IN mitigation involves the iterative reconstruction of residual IN, which is then subtracted from the received signal. Denoising is also applied to the estimated channel impulse response. Thus, channel estimation and IN mitigation are mutually beneficial. Simulation results confirm that the proposed iterative receiver significantly improves the mean squared error of the channel estimation as well as bit error rate. Index Terms-Baseband power-line communication (PLC), channel estimation, impulsive noise (IN), iterative algorithm, noise cancellation, orthogonal frequency division multiplexing (OFDM) 0885-8977 (c)
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