Atika Rivenq

Minimizing energy consumption within wireless sensors networks using optimal transmission range between nodes

Recent advances in wireless communications and electronics have enabled the development of low-power and energy consumption, multifunctional sensor nodes that are small in size and communicate in short distances. These tiny sensor nodes, which consist of sensing and data processing, leverage the idea of sensor networks. Sensor size represents a significant limitation mainly in terms of energy autonomy and therefore of life period, for the batteries have to be too tiny. This is the reason why intensive research is being conducted nowadays on how to control sensor energy consumption within a network, taking communications into account as a priority. For this purpose we have proposed a method to calculate energy consumption within the wireless sensor networks according to the number of information packets sent, the number of nodes and, furthermore, we have succeeded in reducing energy consumption within the sensor networks.

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.

Robust and High Data Rate Wireless Link for Security Between a Bus and a Control Centre

For transport operators today, making passengers and crews feel safer on urban mass transportation systems, and curbing damage to rolling-stock, are two of the main priorities. To satisfy these needs, they rely more and more on surveillance systems based on audio and video sensors which are able to detect automatically potentially dangerous situations and to send an alarm signal, with the corresponding audio and video streams, to the security staff at the control centre. When the system is embedded in a public transport vehicle, the transmission system must be a wireless one and must be able to offer high data rate and high quality of service in order not to cause a deterioration to the audio and video stream. The work presented in this paper concerns the development of such a transmission system from an urban bus to a control centre. Existing telecommunication standards offering large radio coverage generally offer asymmetrical links and none of them is able to support very high data rate in up-link. The new IEEE802.16 or WiMAX (worldwide interoperability for microwave access) standard will offer 3 to 5 Mbps on both transmission directions. The paper will present a 2x4 MIMO transmission system based on the physical layer called PHY-OFDM of IEEE802.16-d with STBC code and turbo processing to increase robustness. Different signal processing solutions were evaluated in simulation with measured propagation channels with various correlation degrees (suburban and urban canyon) representative of urban bus environments. A real transmission system has been built on the basis of the simulation one. Experiments in real conditions were conducted in the centre of Lille in the north of France.

Evaluation of coding's methods for the development of a radar sensor for localization and communication dedicated to guided transport

To explore possibilities of new exploitation modes of automatic guided transport, our laboratories designed formerly a sensor radar called DIREP (Detection et Identification des Rames En Panne: detection and identification of broken-down trains). This system is founded on the principle of a co-operative radar using a transponder inside targets. It is based on a numerical correlation receiver and has a very broad band from 50 to 100 MHz. which remains unexploited. Thus we propose to benefit from this band to establish high flow communication. The proposed system is made of microwave transmitting and receiving equipment fixed on each train, one ahead and other behind. The two trains exchange data and specific signals coded that make the system able: to deduce the distance between the trains; to identify the state of the train (broken-down or not); and to allow the transmission of pictures or audio-video records with a high data flow. The aim of this work is to propose technical solutions for multiplexing communication data and localization code in order to allow high data flow transfer. Simulations are computed to evaluate the systems performance: BER, computing time and complexity.

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.

A Real Time Signal Processing for an Anticollision Road Radar System

This paper describes the real time processing unit used for an anticollision road radar system. This radar based on a numerical correlation between the transmitted signal and the received signal is under development. The signal uses orthogonal codes to ensure a multiple access communication between all vehicles in near area. In this paper, a real time processing unit associated to an original anticollision radar is presented. The studied radar is based on spreading spectrum coded radar waveforms at 76-77 GHz and a numerical correlation receiver. This sensor associated to other sensors like Lidar and Camera will be used on-board vehicles for more safety on road. The studied receiver computes the numerical crosscorrelation between the received signal and a replica of the transmitted code to allow an optimal detection. The appropriate coding and processing have been used to implement a laboratory radar mock-up. The real time processing is tested in order to show their performances and disadvantages when applied to obstacles detection. The main idea is to achieve an efficient real time detection using a simple and low cost system.

Embedded architecture with hardware accelerator for target recognition in driver assistance system

This paper presents a new Radar-based recognition system, which is able to identify obstacles during a vehicle movement. Obstacles recognition gives the benefits of avoiding false alarms and allows generating alarms that take into account the identification of the obstacle in front of the vehicle. In this paper, we first identify hotspots in the target recognition application. Then, we propose an optimized version of the multiple target recognition algorithm to respect the real time constraints of the application while simplifying the underlying hardware platform. We also propose a flexible embedded architecture with hardware accelerator that supports the proposed algorithm. Using a low cost FPGA-based System-on-Chip, our system is able to detect and recognize more than 10 obstacles of different types in a time limit of 25 mSec.

Methods of target recognition for UWB radar

With the growth of embedded components (GPS, radar, cameras…), road vehicle becomes more and more intelligent and reassuring.

Radar based collision avoidance system implementation in a reconfigurable MPSoC

This paper discusses the design and optimization of an FPGA based MPSoC dedicated to Multiple Target Tracking (MTT) aimed at Driver Assistance applications. The use of MTT in DASs has not been sufficiently investigated before. After designing the application we propose a multi-processor system-on-chip (MPSoC) architecture for its physical implementation in FPGA. We formulate strategies to improve the system speed and reduce its demand for configurable resources. We identify performance bottlenecks and gradually optimize the hardware and software to meet system constraints. The result is a complete embedded MTT application running on a multiprocessor system that fits in a contemporary medium sized FPGA device.

Collision avoidance radar system using UWB waveforms signature for road applications

The concept of the intelligent car consists in equipping the vehicle with an optimum number of sensors such as radar, in order to perceive the environment which surrounds it, to ensure an automatic guidance control of the vehicle and to communicate with the external medium. In this paper, we propose to exploit the UWB technology for road radar applications, in order to profit from its inherent advantages (good range resolution, low power consumption, low price etc.). All exiting studies on UWB radar concerns essentially medical and military applications. The originality of this radar is its capacity to detect easily various obstacles and to give their signatures. This paper describes the used radar and presents an interesting study of the adapted UWB waveforms which allow location and signatures of different kind of obstacles detected in short ranges with a good resolution.