Device-Free Localization Using Enhanced Channel Selection and a Distance-Based Elliptical Model

Abstract

Device-free localization (DFL) based on wireless sensor networks (WSNs) is a technology that can detect and locate a person by measuring the changes in received signals without the need for any wireless devices. As an emerging important technology in WSNs, radio tomographic imaging (RTI) has received increasing attention. However, there is much room to improve localization accuracy in RTI. To address this issue, an enhanced channel-selection method and a new distance-based elliptical model are proposed to improve the localization accuracy. The enhanced frequency channel-selection method selects two channels with the lowest received signal strength (RSS) variances to collect data. This approach is more robust to environmental change. The new distance-based elliptical model is based on the distance between the voxels and sensors. Meanwhile, the communication links are divided into line-of-sight (LOS) paths and nonline-of-sight (NLOS) paths. Experimental results demonstrate that the proposed algorithm improves the accuracy of positioning by up to 44.8% over some state-of-the-art RTI methods with low cost.

MA-RTI: Design and Evaluation of a Real-World Multipath-Assisted Device-Free Localization System

“…To cover the target area with a sufficient amount of MPCs, we placed four sensor nodes that were equipped with a UWB radio in the target area. With four sensors, we could localize positions that were in the vicinity of several MPCs with an accuracy of less than 1 m. In addition, with a more realistic weight function for MA-RTI (such as proposed in [ 18 ]), the localization accuracy would be increased in the future.…”

“…As stated before, DFL systems must cope with multipath propagation, otherwise the multipath propagation decreases the localization accuracy. Some authors avoid multipath by measuring the channel measurement over various channels in order to combine the information, or pick the channel that is least affected by multipath [ 4 , 5 , 18 ].…”