Michael Bocquet

Experimental characterisation of IEEE 802.15.4 channel running at 2.4 GHz inside buildings

In order to reduce energy consumption in buildings, sensor networks can be deployed to manage and control equipment in buildings. The WSNs based on ZigBee/IEEE 802.15.4 in the 2.4 GHz ISM (Industry Science and Medical) band, supports low prices and long battery life with moderate rates, low complexity of deployement, and simple data connectivity. The aim of this work is the study and analysis of the radio signals based on the 2.4 GHZ band inside buildings. This study presents optimized channel models based on extensive real hardware measurements of received signal strength value. Several measurement scenarios are considered: corridor, inter-classrooms, inter-offices and laboratory hall. Analysis of these measurements to determine the type of separation in buildings is developed and the validation of the proposed channel models is discussed.

UWB technology applied to millimeter-wave indoor location systems

This study deals with UWB technology applied to location systems operating in the millimeter-wave frequency band. Sub-nanosecond impulse topologies are considered to achieve indoor location systems operating at 60 GHz. For each system, an original focusing technique is implemented to minimize the degradation of the location error due to the impact of the multipath propagation.

Study of the positioning of wireless sensors for communication at 2.4 GHz inside the train

The benefits of wireless sensor networks (WSN) offer many possibilities for the management of energy systems, which are actually based on wired systems. The need of new services on-board the train and of cables lengths reduction promote the use of wireless sensor networks in trains. Then, researches are required to estimate radio coverage to optimize planning before actual network deployment. In this paper, we study a 2.4 GHz propagation channel in a corridor environment which simulates a wagon configuration. The purpose of this work is to determine the best location of these sensors for optimal wireless communication inside the train. Thus preliminary measurements were made in a corridor with seats to prepare the future measurement campaign in a real train. To better analyze this propagation channel, a simplified 3D model of the measurement environment has been developed taking into account material parameters and simplified geometry to validate a simulation model. Finally, measurement results were compared to the simulation ones using on geometrical optics theory.

ZigBee Sensor Network Platform for Health Monitoring of Rails Using Ambient Noise Correlation

WSNs (wireless sensor networks) can be used for railway infrastructure inspection and vehicle health monitoring. SHM (structural health monitoring) systems have a great potential to improve regular operation, security and maintenance routine of structures with estimating the state of its health and detecting the changes that affect its performance. This is vital for the development, upgrading, and expansion of railway networks. The work presented in this paper aims at the possible use of acoustic sensors coupled with ZigBee modules for health monitoring of rails. The detection principle is based on acoustic noise correlation techniques. Experiments have been performed in a rail sample to confirm the validity of acoustic noise correlation techniques in the rail. A wireless communication platform prototype based on the ZigBee/IEEE 802.15.4 technology has been implemented and deployed on a rail sample. Once the signals from the structure are collected, sensor data are transmitted through a ZigBee solution to the processing unit.

Wireless communication between wagons at 2.4GHz

The work presented in this paper is part of general study concerning the connected wagon. The objective is to ensure communications of data associated to wagon (contents, location The aim of this study is to find the most appropriate technology to design a wireless communication between wagons or between wagon and infrastructure. This analysis takes into account railway and embedded systems constraints such as severe electromagnetic environment and low power consumption. The paper presents, at the first part, a state of the art of existing technologies. The second part describes the used technology (ZigBee) and their performances in propagation environment.

Direct path detection algorithm in multiple input single output configuration for transport applications

This paper introduces a novel technique that exploits cross-correlation properties of near-orthogonal pseudonoise (PN) codes to estimate the time of arrival of the direct path signal for Multiple Input Single Output (MISO) applications. Indeed, multipath are a source of error in the time measurement systems. These errors are more significant when the direct path is not the strongest and it is not detected. Transport domain is one of the environment which suffers of mulLtipath effect. The accuracy of the information sent must not suffer from any ambiguity. Therefore find reliable techniques to detect arrival time of signals is vital. Some algorithms proposed to solve this problem use parameters based on complex probabilistic function to estimate time of arrival of the direct path. The most one is General Maximum-Likelihood (GML) algorithm as detector in Ultra Wide Band (UWB) propagation multipath which targets on Single Input and Single Output (SISO) applications. This proposed method has been tested with computer simulations in AWGN and IEEE.802.15.4a indoor channels for low and high Signal to Noise Ratio (SNR). The obtained results show, on one hand, that direct path estimation is function of attenuation factor, and on the other hand, proposed algorithm makes direct path estimation well for MISO configuration accurately.