Nuzzer: A Large-Scale Device-Free Passive Localization System for Wireless Environments

TL;DR

Nuzzer is a large-scale, device-free passive localization system that uses existing wireless networks and probabilistic techniques to accurately locate entities within 1500 square meters with less than 2 meters median error.

Contribution

This paper introduces Nuzzer, a novel large-scale DfP localization system that leverages existing Wi-Fi infrastructure without additional hardware, suitable for real environments.

Findings

Achieves less than 2 meters median localization error

Operates effectively in multipath-rich environments

Uses only two monitoring laptops and three access points

Abstract

The widespread usage of wireless local area networks and mobile devices has fostered the interest in localization systems for wireless environments. The majority of research in the context of wireless-based localization systems has focused on device-based active localization, in which a device is attached to tracked entities. Recently, device-free passive localization (DfP) has been proposed where the tracked entity is neither required to carry devices nor participate actively in the localization process. DfP systems are based on the fact that RF signals are affected by the presence of people and objects in the environment. The DfP concept enables a wide range of applications including intrusion detection and tracking, border protection, and smart buildings automation. Previous studies have focused on small areas with direct line of sight and/or controlled environments. In this paper, we present the design, implementation and analysis of Nuzzer, a large-scale device-free passive localization system for real environments. Without any additional hardware, it makes use of the already installed wireless data networks to monitor and process changes in the received signal strength (RSS) transmitted from access points at one or more monitoring points. We present probabilistic techniques for DfP localization and evaluate their performance in a typical office building, rich in multipath, with an area of 1500 square meters. Our results show that the Nuzzer system gives device-free location estimates with less than 2 meters median distance error using only two monitoring laptops and three access points. This indicates the suitability of Nuzzer to a large number of application domains.