Ismail Ben Mabrouk

MIMO-UWB Channel Characterization Within an Underground Mine Gallery

Multiple input multiple output-ultrawide band (MIMO-UWB) systems are experimentally evaluated for underground mine high-speed radio communications. Measurement campaigns using two different antenna configurations have been made in an underground gold mine. Furthermore, two scenarios, which are the line of sight (LoS) and the non-LoS (NLoS), i.e., taking into account the mining machinery effect, are distinguished and studied separately. In fact, the channel is characterized in terms of coherence bandwidth, path loss, shadowing, channel correlation, and capacity. Results reveal how antenna array configuration affects main channel parameters and suggest that mining machinery presence substantially affects both received power and time dispersion parameters within the underground mine and should, therefore, be considered when assessing the performance of in-gallery wireless systems. Moreover, it is shown that the MIMO-UWB takes benefit of the large spreading bandwidth and the multipath propagation environment to increase the channel capacity.

Performance Evaluation of a MIMO System in Underground Mine Gallery

This letter studies the use of multiple-input-multiple-output (MIMO) systems for underground mine communication. Measurement campaigns using directional (patch) and omnidirectional (monopole) antennas have been made in a real gold mine. Furthermore, the channel is characterized in terms of Rician K-factor, channel correlation, and capacity. Results suggest that in such a scatter-rich environment, the directional antennas have shown to provide significant suppression of multipath signals and a corresponding increase in the correlation. However, thanks to its higher antenna gain, the patch antennas present better channel capacities.

Characterization of an Off-Body Channel at 2.45 GHz in an Underground Mine Environment

Underground mines are challenging environments for off-body wireless communication, since the signal propagation is majorly affected by small scale and large scale fading. The use of multiple antennas at the transmitter and the receiver sides is a known technique to combat fading and enhance capacity. In this paper, the channel parameters of a 2 × 2 Multiple-Input Multiple- Output (MIMO) off-body system are investigated in an underground gold mine and compared to the Single-Input Single-Output (SISO) system parameters. Measurement campaigns were conducted using monopole antennas at a center frequency of 2.45 GHz for both Line Of Sight (LOS) and None Line of Sight (NLOS) scenarios. The measured frequency responses are converted into impulse responses through an Inverse Fourier Transform (IFT). The results show that for a constant transmitted power, the path loss exponents at NLOS are smaller than their counterpart values at LOS. The channel capacity values decrease as the propagation distance increases and when the link is obstructed at NLOS. The RMS delay spread is generally increasing with distance for both LOS and NLOS situations. When a fixed Signal-to-Noise Ratio (SNR) is assumed, MIMO topologies improved the SISO capacity by roughly 8 bps/Hz. The channel characterization results demonstrate that the MIMO configurations provided a remarkable improvement in terms of capacity, coherence bandwidth, and time delay spread compared to the SISO topologies.

Experimental Characterization of a Wireless MIMO Channel at 2.4 GHz in Underground Mine Gallery

This paper deals with several aspects relative to the Multiple-Input Multiple-Output (MIMO) propagation channel. Measurement campaigns, made in a real gold mine at 2.4GHz under line-of-sight (LOS) and non-line-of-sight (NLOS) scenarios, have been analyzed to obtain the relevant statistical parameters of the channel. It was shown that the MIMO exploit the multipath propagation in rich scattering environment to increase the capacity. Hence, the channel is characterized in terms of K-factor, path loss, shadowing, and capacity. Results show a propagation behavior that is speciflc for these underground environments with rough surfaces.

MIMO channel characterization at 2.4 GHz in underground gold mines

This paper deals with several aspects relative to the Multiple-Input Multiple-Output (MIMO) propagation channel. Measurement campaigns, made in former gold mine at 2.4 GHz, have been analyzed to obtain the relevant statistical parameters of the channel. These results make it possible the use of MIMO techniques in real underground mine gallery for wireless communication systems.

Characterization of a NLOS Off-Body Channel at 2.45 GHz Using Patch Antenna Inside a Mine

In underground environments, the safety of the miners depends on the quality of the used communication systems. Currently, wireless underground communications suffer from small-scale and large-scale fading, compromising the propagation quality and limiting the achieved bit rate. In this paper, the performance of a patch antenna set in off-body channels under None Line of Sight (NLOS) conditions is evaluatedat a frequency of 2.45 GHz. Measurement campaigns were performed in a gold mine in order to determine the channel parameters for NLOS configurations and compare them with previously published Line Of Sight (LOS) results. Hence, the channel parameters were determined from the measured frequency responses. The off-body channel is characterized in terms of the impulse response, path loss, RMS delay spread, coherence bandwidth, and channel capacity.

EXPERIMENTAL CHARACTERIZATION OF WIRELESS MIMO CHANNEL AT 5.8 GHz IN UNDERGROUND GOLD MINE

This paper presents analysis results relative to an underground MIMO channel. Measurement campaigns were conducted in a former gold mine at a center frequency of 5.8GHz under Line- Of-Sight (LOS) scenario. Extracted data have been processed to obtain the relevant statistical parameters of the channel. The resulting propagation behavior difiers from frequently encountered in more typical indoor environments, such as o-ces and corridors. Indeed, the path loss exponent is less than 2 in MIMO conflguration due to the large number of scatters that increase the received power when compared to the free-space case. Moreover, there has been a signiflcant increase in spectral e-ciency, when using MIMO technique. Hence, according to calculated statistical parameters, wireless link performance is improved through the use of the MIMO scheme. All in all, multi antenna systems present an ideal alternative for future underground communication systems.

EXPERIMENTAL CHARACTERIZATION OF A MIMO UNDERGROUND MINE CHANNEL AT 2.45 GHz

In this paper, an experimental characterization of a MIMO underground channel is presented. A simple statistical model is proposed at 2.45GHz. The channel is characterized in terms of path loss, shadowing, RMS delay spread, and capacity. The measurements are carried out in an underground mine, which is a harsh conflned environment. The path loss model is extracted from measured data for the line of sight (LOS) and non-line of sight (NLOS) scenarios for both MIMO and SISO channels. The path loss exponent in LOS is less than 2 in MIMO and SISO as the environment has a dense concentration of scatterers. A statistical study is carried out to flnd the delay spread. For MIMO and SISO, there is no relation between the delay spread and the transmitter receiver distance. Furthermore, the delay spread of the MIMO is less than the one of the SISO channel in the LOS measurement campaigns. Aikake information criteria are used as a goodness of flt for difierent statistical distributions to represent the delay spread. According to the calculated capacity for a constant signal to noise ratio in LOS case, the transmission performance is signiflcantly improved by using the MIMO scheme over the traditional SISO. Therefore, MIMO is an ideal candidate for future wireless underground communications.

Experimental characterization of MIMO-UWB multipath underground mine radio channels

This paper reports on experimental results and its interpretations for MIMO-UWB multipath channel. It is intended to help in establishing design guidelines for underground mine wireless communications systems using MIMO-UWB technology. It deals with measurements obtained using two different antenna configurations under line-of-sight (LOS) conditions. Furthermore, the MIMO channel is characterized in terms of channel correlation and capacity. It was shown that a special arrangement of antennas in a MIMO system may reduce channel correlation and improve capacity.

Progress Research on Wireless Communication Systems for Underground Mine Sensors

After a recent series of unfortunate underground mining disasters, the vital importance of communications for underground mining is underlined one more time. Establishing reliable communication is a very difficult task for underground mining due to the extreme environmental conditions. Nevertheless, wireless sensors are considered to be promising candidates for communication devices for underground mine environment. Hence, they can be useful for several applications dealing with the mining industry such as Miners’ tracking, prevention of fatal accident between men and vehicles, providing warning signals when miner entering the unsafe area, monitoring underground gases, message communication, etc.