Pierre-Martin Tardif

Security Monitoring Using Wireless Sensor Networks

The underground environment is a harsh and hazardous workspace for plant and personnel. It is damp, dusty and hot, there is a risk of roof and rock falling and the atmosphere can be potentially explosive. Recent incidents are a reminder of how crucial safety is in mining. The increasing miniaturization of RF devices and micro-electromechanical systems (MEMS) and the advances in wireless technologies have generated a great deal of research interest in the area of wireless sensor networks (WSN). Sensor networks provide a promising infrastructure for gathering information about parameters of the physical world. Such networks have many applications in military and civilian environments. In this paper, a new wireless sensor network architecture is introduced for surveillance and security monitoring of underground mines and confined areas.

Application of Ad-hoc sensor networks for localization in underground mines

Underground mining is a hazardous industrial activity. The harsh physical environment and distinct topology that make mining dangerous act as a hindrance or constraint to the very techniques and technologies that could improve safety and productivity. Workers safety is of paramount importance and is certainly a moral obligation for any business! Wireless sensor networks monitoring is an application that is very crucial for the safety of mine workers. These sensors can monitor vital life signs of workers which may be very useful during emergency situations. Localization and tracking of moving objects is an essential capacity for a sensor network in many applications. This paper studies the problem of localization in underground mines using ad-hoc sensor networks. We use the DV-hop algorithm to estimate the distance between a mobile node and a fixed anchor and we apply the bounding box technique to estimate the location

On the TOA Estimation for UWB Ranging in Complex Confined Area

This paper addresses ranging in quasi-static environments and presents a time of arrival (TOA) based ranging algorithm. An accurate estimate of signal arrival time is considered essential in time-based wireless and indoor location systems. Super-resolution techniques are applied to the general problem of temporal analysis of the received signal. For this study an experimental model of a UWB multipath channel collected in an underground mine is used. In particular, we are interested in the estimation of the TOA, which is by definition the time delay of the first path. For this purpose, we apply MUltiple Signal Classification (i.e., MUSIC algorithm) to estimate all delays and then decide to retain the first one as the time of arrival. The performance in terms of absolute error is measured. The sensitivity of the estimated TOA with different bandwidths is also evaluated.

Cross-layer link adaptation design for UWB-based sensor networks

A routing protocol is essential for the success of wireless sensor networks (WSNs). Its task is to ensure a reliable communication between neighbouring nodes, and to transmit data (via an intermediate node) form any node to the central node. However, unlike traditional ad hoc networks, WSN are energy constrained since nodes operate with limited battery capacity. Thus, the routing protocols for WSN must be designed with a focus on the energy efficiency criterion. This paper presents a cross-layer link adaptation scheme for an energy efficient routing protocol for ultra-wideband (UWB)-based sensor networks. We use a joint consideration of physical and multiple access layer in order to minimize the energy consumption of the network, and hence increasing its lifetime. Multiple accesses are assumed to have a UWB time-hopping signalling structure. Our goal is to define the link adaptation as a numerical optimization in which the energy consumption of a multihop route is taken into account.

Eigen-Analysis of UWB Channel on the Basis of Information Theoretic Criteria

Underground mine galleries can be considered as complex transmission lines where multipath, attenuation, reflection, diffraction and scattering effects are dominants. However, some companies have started to deploy modern wireless system networks in mine galleries with the objective of increasing safety and productivity. In the last decade, ultra-wideband (UWB) technology has gained much interest for its application to wireless communications. This paper reports on experimental results of UWB channel propagation in an underground mine. Eigen-decomposition and subspace-based statistical signal processing on the autocorrelation matrix of the channel impulse response are used. We apply information theoretic criteria to estimate the number of significant eigenvalues. This result is then used to calculate the RMS delay spread of the channel.

An interactive Java applet for teaching discrete-time system theory

In this paper we present a Java applet used for teaching discrete-time system theory to electrical and computer engineering students. The objective of the applet is to show students the relation between the position and number of poles and zeros in the Z-plane with the frequency and impulse responses of the linear system defined by these poles and zeros.