Gilles Y. Delisle

Experimental evaluation of the ultra-wideband propagation channel in an underground mine

This paper presents a characterization of the ultra-wideband (UWB) propagation channel in an underground mining environment over a frequency range of 3 GHz to 10 GHz‥ Both LOS and NLOS measurements are considered at two corridor depth levels of 40m and 70m The results are based on experimental data obtained during an extensive measurement campaign in the UWB frequency range where the path loss exponent and the coherence bandwidth are used for comparison purposes as a function of the physical depth of the channel. This lead to a simple model sufficiently accurate to characterize the statistics of the received signal in an underground mine.

Wi-Fi-based positioning in underground mine tunnels

The Owl Positioning System (OwlPS) was originally designed as a general-purpose Wi-Fi-based indoor positioning system. It is also a tool to compare several positioning techniques from the same input data, and was used for this purpose in previous work. In this work, OwlPS is adapted to a very specific “indoor” environment, namely underground mine tunnels, which brings its own problematics in terms of radio signal propagation and therefore impacts positioning system design. Experiment were conducted at a formerly exploited gold mine, at 70 metres under ground level, across about 400 metres of drifts. Several scenarios were defined to mimic typical use cases.

Large-scale characterization of an underground mining environment for the 60 GHz frequency band

In order to improve the mining communication applications such as video with high data rates, a characterization of the underground mining channel was done. The use of the IEEE.802.15.3c standard with an OFDM modulation scheme for the 60 GHz can allowobtaining a data rate range from 31.5 Mbps to 5.67 Gbps. This paper provides the propagation characteristics of the mine, which is a complex electromagnetic environment, necessary to the deployment of networks in the IEEE.802.15.3c or the IEEE.802.11ad standard. The experimental results were obtained during an extensive measurement campaign over a frequency range of 61 GHz to 63 GHz in an underground mining environment. These results allow the extracting of the large scale parameters such as the path loss exponent which help to design wireless communication systems. The line of sight (LOS) measurements were performed in the middle of the gallery. Finally, a comparison of the results obtained in a mining environment and in a laboratory is done. The path loss exponents are less than 2 in both scenarios as the environments have dense concentration of scatterers.

A novel piezoelectric micro-generator to power Wireless Sensors Networks in vehicles

This paper proposes an autonomous power supply to feed the nodes of a Wireless Sensor Network (WSN) used in vehicles. The vibration levels detected in a moving vehicle in an urban or semi urban area are used as the primary form of autonomous energy. Measurements show that a maximum power density of -16.9 dB/Hz is observed around 15 Hz for cruising speed up to. Our design is based on a cantilever piezoelectric transducer 90 km/h mechanically adjustable in frequency designed and manufactured to resonate very close to 15 Hz. Experimental results clearly demonstrate a level of energy sufficient to adequately supply power to a wireless sensor node. Specifically, for an optimum load resistance of 73.13 kΩ, a power of 3 μW is achieved by our autonomous supply.

Characterization of the 60 GHz channel in underground mining environment

This paper presents the first results at 60GHz of the path loss characterization in underground mining environment. The results are based on experimental data obtained during a measurement campaign using a frequency range from 60 to 62 GHz and a simple path loss model is used to characterize the large-scale fading of this type of environment.

High gain cross DRA antenna array for underground communications

This paper presents the design of a high gain cross DRA array antenna (AXDRA) with a novel feeding method based on microstrip transmission line for millimeter-wave operation. Simulation results shows that the AXDRA achieves an impedance bandwidth from 57.5 GHz to 63 GHz covering ISM band, and gives an appreciable gain of 15.5 dBi, found to be stable within the passband. The size of the whole antenna structure is about 25mm×25mm and is therefore small enough to be used in underground communications systems. The simulation process was done using Computer Simulation Technology (CST) Microwave Studio.

Circular polarisation XDRA for broadband underground communications

A dielectric resonator antennas (DRA) is good candidate to achieve a performant millimeter band antennas. They can provide larger band smaller size, but their performances when used for circular polarisation are still limited. The proposed antenna XDRA is composed of a superstrate, an aperture feed and a cross dielectric resonator. This antenna is designed to cover the ISM frequency band at 60 GHz (57 GHz-65 GHz), is shown to deliver an impedance bandwidth ( S11 <;-10 dB) of 20.5%, from 56 to 68 GHz and an axial-ratio bandwidth (AR <; 3 dB) of 15%, from 58 to 63 GHz. , and a gain of 18 dB found to be stable within the passband. Results are obtained using two different electromagnetic simulators (CST Microwave Studio and Ansoft HFSS).

UWB-SIMO channel capacity in an underground mine

This paper presents an evaluation of the ultra-wideband (UWB) channel capacity in an underground mine. A measurement setup was established to measure the channel frequency response both in LOS and NLOS. The measurements were performed at level -70 m in an experimental gold mine. The SISO (single input single output) channel capacity was first determined, followed by the SIMO (single input multiple output) capacity with receiving antennas. The measurements results reveal that the channel capacity can support high data rates. Also, it decreases with the distance between transmitter and receiver. The result shows also that increase of the capacity of a SIMO channel is not linear with the number of receiving antennas.

Experimental characterization of the Underground UWB channel

Results from parametric modeling of the indoor channel frequency response for very large number of sweeps over a frequency range of 3 GHz to 10 GHz are presented. The characterization of the frequency-dependence of the ultra wideband mining channel across the considered bandwidth is addressed and the smooth frequency response is evaluated using an Auto Regression (AR) method, which is proved in this study, sufficient to better approximate each recorded frequency response. This study concludes that the number of poles needed to describe the AR process is always less than 2 in the studied area. The appropriated poles of the model are obtained by minimizing the root means squared error (RMSE) between the original frequency response measurement and the predicted one. It is finally found out that the frequency decaying factor (δ) is around 0.5 in the underground area on study.