NLOS-Aware VLC-based Indoor Localization: Algorithm Design and Experimental Validation

Abstract

The Visible Light Indoor Positioning System (VL-IPS) has been a popular research area recently. In VL-IPS, many localization methods have been proposed by leveraging the Received Signal Strength (RSS) based trilateration. However, the traditional RSS based trilateration localization (RSS-TL) method is very sensitive to the lighting environment and would results in a big localization error due to the presence of nonline-of-sight (NLOS) light signal. In light of this, we propose a novel NLOS-aware localization algorithm, namely Enhanced Fingerprinting-aided RSS-TL (EFP-RSS-TL). It permits to improve the localization accuracy for the corner regions of a room by eliminating the NLOS impact while keeping the same high accuracy for the room center. This is achieved by leveraging a RSS fingerprint database which records the line-of-sight (LOS) light power ratios beforehand. For validation purpose, we built a real VL-IPS platform and implemented the proposed algorithm. Experimental results show that the proposed NLOS-aware EFP-RSS-TL algorithm enables to reduce significantly the average positioning error (by up to 79%) compared to its counterparts. Besides, our proposal cuts the database size by 50% and is more robust to environment changes. In a room of 4.7 m x 2.7 m, the achieved average positioning error is around 6 cm when it is vacant and it is no more than 14.5 cm when it is occupied by several people.

Target 5G visible light positioning signal subcarrier extraction method using particle swarm optimization algorithm

“…Once environment indexes of all LEDs on all reference points have been extracted completely, the sets Λ and P (equations (4) ( 5)) are obtained and applied to train the classification model. This model builds up the mapping between environment indexes and the PRSs power shown in (6). In this paper, an one-against-all Multi-SVM classifier [15]…”

“…Visible light positioning(VLP) is considered as the most promising candidate of 5G indoor LBS because of many attractive features such as high level of security [5], long system lifetime [6], no radio frequency interference [7] and low cost [8]. VLP system uses the received signal as positioning reference signal(PRS), the input of the position system, to calculate the receiver's position.…”