Abdellah Chehri

UWB-based sensor networks for localization in mining environments

Wireless sensor networks (WSN) have attached a great attention in the last few years. WSN offer several advantages over the traditional sensor networks, such as elimination of costly wires, security and larger area coverage. In the last few years, there has been great interest commercial applications based on Ultra Wideband (UWB). It has potentially low complexity, low cost and an excellent time domain resolution which facilitates location and tracking applications. Therefore, UWB provide a good combination of high performance with low complexity for WSN applications. Localization has attracted considerable attention in many fields. Accurate estimation of an individual location can be a difficult task, producing ambiguous results particularly in harsh environment. In this paper, we focus on feasibility study (via simulation and measurements) of using UWB based-WNS as future solution for localization in underground mines.

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.

Design of wireless sensor network for mine safety monitoring

The recent emergence of the sensor networks technology is significantly impacting the capabilities for automated distributed monitoring of environments. The low manufacturing cost of sensors, increased coverage and accuracy in distributed sensing due to their large deployments and their ability to operate in inhospitable terrains has made them an amenable technology for various surveillance and monitoring applications In this paper we evaluate the performance of wireless sensor network technology for underground mines safety monitoring. The system is mainly composed of static ZigBee nodes, which are deployed on the underground mine galleries for measuring underground mine parameters such as ambient temperature, fire detection, humidity, level of carbon monoxides etc. The main characteristic of the networks such as the throughput, the received data rate, latency have been evaluated.

Large-Scale Fading and Time Dispersion Parameters of UWB Channel in Underground Mines

RF channel measurements in underground mines have important applications in the field of mobile communications for improving operational efficiency and worker safety. This paper presents an experimental study of the ultra wideband (UWB) radio channel, based on extensive sounding campaigns covering the underground mine environment. Measurements were carried out in the frequency band of 2–5 GHz. Various communication links were considered including both line-of-sight (LOS) and non-LOS (NLOS) scenarios. In this paper, we are interested in more details of the variations of the RMS delay spread and mean excess delay with Tx/Rx separation, and the variation of RMS with mean excess. The distance dependency of path loss and shadowing fading statistics is also investigated. To give an idea about the behaviour of UWB channel in underground mines, a comparison of our approach with other published works is given including path loss exponent, shadow fading variance, mean excess delay, and RMS delay spread.

Experimental Testing of IEEE801.15.4/ZigBee Sensor Networks in Confined Area

The IEEE 802.15.4/ZigBee standard is considered as a potential candidate for wireless sensor and actuators networks. Several commercial platforms with IEEE 802.15.4/ZigBee support have been made available in the last few years, and an increasing number of operating systems specifically designed for sensor and actuator networks are evolving. Underground mining is considered to be one of most hazardous industrial activity. The industrial automation applications in the mining galleries can benefit from the recent technological advances. In fact, many approaches to reduce costs and improve performance have been examined. The main objective of this paper is the implementation and evaluation of wireless sensor networks for environmental data measurements in a real underground mine. Therefore, the nodes were evaluated in real operating conditions.

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

An empirical link-quality analysis for wireless sensor networks

Wireless Sensor networks (WSNs) are composed of small hardware devices that possess the ability to measure and exchange a variety of environmental data. In this paper, we measured the radio characteristics of IEEE 802.15.4 for wireless sensor networks. The system is mainly composed of mobile and static ZigBee nodes, which are deployed on the underground mine galleries. Based on measured data, we describe the link characteristics such as received signal strength, latency and throughput for different scenarios. We consider the impact of these findings on the design of WSN for monitoring applications in underground mines.

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.

Radio channel characterization through leaky feeder for different frequency bands

Since several years, communications between fixed and mobile units have been studied in areas in underground tunnels. The leaky feeder (LF) is one of the most useful results of these studies. The LF technology in combination with other communication systems allows us to reduce the transmission power of the mobile entities without sacrificing quality of service. Because the leaky feeder cables are able to transfer both power and RF signal; these technologies are considered as particular case of line power communication. In this paper we present and analyze the results of narrowband and wideband radio channel characterization. The measured frequency bands are selected for uses in several applications (WPAN, CDMA, video and analog telephony). The measurement were performed in underground mine gallery.

Service-oriented architecture for smart building energy management

Energy consumption in the residential sector is a considerable source of a wide range of environmental problems. It has been mentioned that the energy consumption in this sector represents 46% of total energy consumption and 23% of greenhouse gas emissions. Technology and services can help consumers manage the energy generated by their renewable or traditional electric grid. Service oriented architecture (SOA) has recently become very popular. SOA is an approach to build distributed systems that deliver application functionality as services to end-user applications or to build other services We adopt an approach to formulate the problem of managing energy in the building in a general form of linear programming by optimizing three criteria: environmental, economic and user comfort. First, we formulate this problem into an integer linear programming (ILP) problem. A round-up heuristic algorithm which is based on linear programming relaxation is presented.