Fouzia Elbahhar

Time-Reversal UWB Wireless Communication-Based Train Control in Tunnel

This paper reports an evaluation of UWB radio technology and Time-Reversal (TR) technique in tunnel environments for train-to-wayside communication. UWB technology has the potential to offer simultaneous ground-totrain communication, train location and obstacle detection in front of the trains. Time-Reversal channel pre-filtering facilitates signal detection and helps reduce interference. Thus, UWB-TR combination provides a challenging, economically sensible, as well as technically effective alternative solution to existing signaling technologies used in urban transport systems. This paper deals with deterministic channel modeling and its characterization in tunnel environment. It reports simulation performance evaluation of UWB-TR combinations in the developed channel model.

Wide-band indoor localization effectiveness in presence of moving people

Recently, new standards have emerged in the telecommunication industry. These standards provide an open global specification that enables mobile devices to access and interact with information and services instantly. Paving the way to the emergence of new added-values services, these devices require more and more a localization agent. When deployed, these wireless resources have to operate in non-stationary propagation conditions and from outdoors to indoors. This paper concentrates on the evaluation of UWB radio signals used for localization, in presence of moving people modifying the indoor propagation channel. Different frequencies, bandwidths and densities of moving people are considered. Impacts of these parameters are evaluated on two different ranging methods: time of arrival (TOA) based and received signal strength (RSS) based.

Evaluation of a Tunnel Ground to Train UWB Communication

This paper considers the use of the UWB radio technology for railway signalization. UWB potentially offers simultaneous ground to train communication, train location and obstacles detection using basically the same radio technology. This paper concentrates on the communication issue. It theoretically starts an evaluation of the performances of such UWB signals propagating into a railway tunnel. The first part of this paper presents some conventional UWB waveforms that could be used to propagate efficiently into a railway tunnel environment. A second part develops the propagation model used in order to simulate the frequency selective tunnel channel propagation. A third part presents the effect of this frequency selective tunnel propagation on these original waveforms. Considering different modulation schemes, some receiving performances are then analyzed.

Performance analysis of Doppler shift impact on the MB-OFDM system applied for vehicle to infrastructure communication

The MB-OFDM is an attractive radio technique with high data rate transmission over short ranges. However, Inter-Carrier Interference (ICI) resulting from Doppler shift phenomenon degrades the MB-OFDM system performance in terms of Bit Error Rate (BER) and the transmission range. In this paper, the Doppler shift impact on the MB-OFDM system is studied and analyzed over AWGN channel. Two ICI cancellation schemes namely the Extended Kalman Filter (EKF) and the Maximum Likelihood (ML) estimation have been proposed to improve the signal quality and the transmission range. It is shown that the EKF algorithm performs better then the ML method and gives good results in terms of the signal quality and it can effectively enlarge the transmission range.

UWB System Based on the M-OAM Modulation in IEEE.802.15.3a Channel

Known for many years but unexploited in the field of communications, ultra wideband systems (UWB) can be a solution to the saturation of the frequency bands. The advantage of such systems is that they are inexpensive in energy because of the limitations imposed by the standard. Our work is to design a high data rate IR-UWB system, through the use of modulation M-OAM (Orthogonal Amplitude Modulation), and the study of the system performances by adding the effect of the propagation channels dedicated to the UWB. The channel modeling is an important step in the implementation of any system, especially for those in development, as is the case of UWB systems. Although this model is one of the key elements of the overall chain system, it must take into account the distance between the two antennas, multipath and signal type. In this paper, we discover the existing models suitable for UWB channels and their implementation on our M-OAM system. The introduction of real channels in our chain of transmission reduces the quality of our system. Therefore, a RAKE receiver is proposed as a solution to improve performance.

Assessment of the Contribution of Time Reversal on a UWB Localization System for Railway Applications

UWB radio has the potential to offer good performance in terms of localization precision. Time Reversal channel pre-filtering facilitates signal detection and also helps to increase the received energy in a targeted area. This paper assesses the quantitative and qualitative contributions of the Time Reversal (TR) technique associated with an Ultra Wideband (UWB) localization system applied to a railway odometry problem. The analytical and simulation results for Power Delay Profile, equivalent channel model and focusing gain of the TR-UWB are given. The contribution of the TR technique associated with UWB radio to enhance the localization resolution is analysed. To perform these studies, and to be representative of the proposed railway application, a deterministic channel model is used. The analytical simulation and experimental results show that time reversal has very promising characteristics regarding its association with the UWB in terms of localization error. These results also indicate that the TR-UWB technique delivers improved performance over UWB only localization approach, that could benefit the development of the proposed railway application.

UWB Radar for Railway Fall on Track Object Detection and Identification

This paper presents a new system for detecting and identifying objects fallen onto railway tracks. The proposed solution is based on an ultra-wideband (UWB) radar technique combined with a long travelling wave radiating microwave transmission line. This line is maintained adequately all along the railway station platform. Scheduled steps for system realization are presented. A preliminary analysis of different transmission lines which could be used and their performance is provided. Automatic Target Recognition (ATR) application, which describes identification procedure, is discussed. An overview of extraction methods is provided and a procedure of selection of contributing poles is presented. Available target identification techniques based on UWB pulse are analyzed and compared to experimental results.

Multi-User, Time-Reversal UWB Communication for Railway Systems

In this paper we propose to apply Time Reversal (TR) technique and UWB radio technology for railway signalization systems. UWB technology has the potential to offer simultaneous ground-to-train communication, train location and obstacle detection in front of the trains. Time Reversal channel prefiltering facilitates signal detection and helps to reduce interference effect. Thus, UWB-TR combination provides a challenging, economically sensible, as well as technically effective alternative solution to existing technologies used in signaling systems. This paper concentrates on the communication question and reports a performance evaluation of such combinations in a railway tunnel. A new approach is also proposed to ensure multiple access MA communication using modified-orthogonal-functions-based waveforms.

Performance Evaluation of High Data Rate M-OAM UWB Physical Layer for Intelligent Transportation Systems

In this paper, a high data rate modulation scheme for impulse radio ultra-wideband (IR-UWB) communication system using orthogonal waveforms is presented. The proposed M-state Orthogonal Amplitude Modulation (M-OAM) is evaluated under additive White Gaussian noise and indoor multipath channels IEEE.802.15. The simulation results show that the proposed system performance, in term of bit error rate (BER), is of the same order as that of the traditional UWB modulation. In addition, the M-OAM modulations provide a high data rate for short range wireless applications. Nevertheless, the multipath effect reduces the quality of transmission. Thus, the performances of three receiver architectures, that employ different pulse combining schemes, are investigated. Namely, a conventional matched filter receiver, a RAKE receiver and a minimum mean square error equalizer are considered. This study shows that the proposed M-OAM communication system offers good performances in term of quality of services, channel capacity and BER.

Energy Efficiency Analysis of a TR-UWB System

In wireless communications, where sensors operate on batteries, the energy consumption must be reduced while considering the communication range and data rate requirements. In this context we analyze and compare, in this study, the UWB and TR-UWB system in terms of the total energy consumption. So, for that, we develop an analytical model to estimate the energy consumption of a UWB system using a TR technique. We then compare the consumption of a TR-UWB system and a UWB system in two different propagation environments. We show that the TR-UWB system is more energy efficient than the UWB system in the chosen environments for LOS. However in case of NLOS, TR-UWB is more efficient when we use a bi-symbol modulation for different ranges of distance in both environments.