ISSN : 1796-2021
Volume : 4    Issue : 4    Date : May 2009

Special Issue: Wireless Communications in Underground and Confined Areas
Guest Editors: Hasnaâ Aniss, Nadir Hakem, Charles Despi, and Larbi Talbi

Hasnaâ Aniss, Nadir Hakem, Charles Despi, and Larbi Talbi
Page(s): 211-213
Full Text:
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Wireless communications are currently omnipresent and their complete pervasiness is often described as the next
telecommunications frontier. As such, confined environments have received much attention as such particular
environments present significant opportunities and markets niche for the wireless industry. The mining industry, with its
worldwide presence and considerable impact, is such a market. Wireless technology can be an important lever to
improve the competing advantage of the mining industry in developed countries and to increase operational safety in
emerging economies. In fact, telecommunication is the principal asset for automation in the mining industry, allowing
the establishment of a global operating program with localization and remote control of mobile equipments. The
specific characteristics of the underground environment, and other types of confined surroundings, present important
design challenges and are at the origin of novel research orientations. This conference targeted university researchers
and industry specialists having realized or interested by original research and innovative applications, or by the analysis
of in-situ experiments, related to telecommunications in a confined area (basement, vehicle) or an underground
environment (for example urban basement, tunnel, underground city, mine, shelter).

This special issue presents nine selected papers from the International Conferences on Wireless Communications in
Underground and Confined Areas, held in Val-d’Or, Canada, 25-27 August 2008. The guest editors selected the best
papers from the communications track of the Conference. The authors of these selected papers produced extended
versions of their conference papers, which were further developed through two rounds of reviews.

Wireless communication system performance in confined areas is significantly influenced by its peculiar channel
propagation characteristics. The ability to identify propagation phenomena by proposed propagation models or
experiments enables the adaptation of communications system design for these areas. Furthermore, the accuracy of
these models impacts propagation ranges, threshold reception, adaptation of dynamic links and the performance of
multiple antennas with spatial multiplexing techniques in such environments.

As presented in paper 1, “Radio Wave Propagation in Arched Cross Section Tunnels – Simulations and
Measurements”, by E. Masson et al., wireless communication systems have been developed for train infrastructure
communication needs related to railway or mass transit applications. These systems are able to operate in tunnel
environments. In this context, specific radio planning tools have to be developed to optimize system deployment.
Realistic tunnels geometries are generally of rectangular cross section or arch-shaped. Furthermore, they are mostly
curved. In this paper, the authors propose an approach to model radio wave propagation in 2.4 GHz and 5.8 GHz
frequency bands in straight arch-shaped tunnels using tessellation in multi-facets. While paper 1 gives a model based on
a Ray Tracing tool using the image method, paper 2, “Modified 2D Finite-Difference Time-Domain Based Tunnel Path
Loss Prediction for Wireless Sensor Network Applications”, by Yan Wu et al., presents a Propagation Path Loss (PL)
Model, which describes the power loss versus distance between the transmitter and the receiver for the tunnel
environment. In this paper, experimental results obtained from conducting close-to-wall measurements at 868MHz and
2.45GHz in curved arched-shaped tunnels are presented along with predictions made using a newly proposed modified
2D Finite-Difference Time-Domain (FDTD) method.

Paper 3, “Modeling and Understanding MIMO propagation in Tunnels”, by Jose-Maria Molina-Garcia-Pardo et al.
presents an application of modal theory for interpreting experimental results of the electromagnetic field variation along
a tunnel. The transmitting frequency is assumed to be high enough so that the tunnel behaves as an oversized
waveguide. Then, for a Multiple-Input Multiple-Output channel, theoretical results of the channel capacity are given.

Paper 4, “On the importance of the MIMO channel correlation in underground railway tunnels”, by Y. Cocheril et al.,
deals also with MIMO channel modeling according to the correlation level in underground railway tunnels for various
antenna configurations for the transmitting and receiving arrays. MIMO channel matrices have been computed with a
3D ray-tracing based software at 2.4 GHz and 5.8 GHz in two different tunnel environments.

Paper 5, “Time-Reversal UWB Wireless Communication-Based Train Control in Tunnel”, by Hassane Saghir et al.,
reports an evaluation of UWB radio technology and Time-Reversal (TR) technique in tunnel environments for train-towayside
communication. UWB technology has the potential to offer simultaneous ground-to train communication, train
location and obstacle detection in front of the trains. This paper deals with deterministic channel modeling and its
characterization in tunnel environment.

Another research area for wireless underground communication is Through-The-Earth (TTE) communication as
presented in paper 6, “Improving Medium Access In Through-The-Earth VLF-LF Communications”, by Vanessa
Bataller et al.

Most research advances in these areas are related to a final application. As presented in paper 7, “Radio proximity
detection in a WSN to localize mobile entities within a confined area”, by Chakib Baouche et al., a solution to localize
mobile entities within a confined area consists in deploying a Wireless Sensor Network (WSN), made of energy-
autonomous devices. The authors propose that the position of a mobile be given relatively to a set of tag nodes deployed in
the zone of activity and signaling their position. In a symmetrical way, each mobile node is announced periodically thus
allowing for mutual detection of radio proximity (tag-mobile or mobile-mobile). During contact, the nodes are able to share
and store the information required by the localization application. This information is then largely scattered by using the
mobility of modes to carry data up to the application collection points. This leads to the issue of the choice of the medium
access method and its performance for proximity detection in a cell covered by a tag node.

While paper 7 focuses on network properties to locate a mobile, paper 8, "Neural Networks for Fingerprinting-Based Indoor
Localization using Ultr-Wideband", by Anthony Taok et al., discusses the use of neural networks in an underground radio-
localization system using UWB as the physical wireless propagation medium and combined with fingerprinting-geolocation
and neural network techniques.

The last paper, "A Novel Interference Safety Margin For cognitive Radio manet Using Smart Antennas", by Mathieu Boutin et
al., proposes a new interference estimation technique for the deployment of a smart-antenna-equipped MANET (Mobile Ad
hoc NETwork), acting as a secondary network, sharing the same scarce frequency band as many legacy fixed antennas
(primary network) in the same area. The proposed technique offers great potential, for the deployment of a cognitive MANET,
since advances in milimeter radio waves technologies will soon make smart antennas easily portable in size.

In closing, we would like to thank reviewers and authors, who, indifferent ways, have contributed to this Special Issue. We
would like to acknowledge all the other authors who have submitted their contributions for this issue. We also acknowledge
the exceptional effort by the Editorial Board of the Journal of Communications throughout this process.

Index Terms
Special Issue, Wireless Communications