UPThèses

English

Optimization of a sensor network by cooperative MIMO techniques

Wireless sensor networks (WSN) have a wide range of applications in various fields and consist of a large number of low-cost, low-power distributed sensors. Energy efficiency of sensors is the most critical issue in the system design of the network. The aim of this thesis is to study the application of recent MIMO techniques in the context of cooperative MIMO forWSN in order to reduce energy consumption. These techniques are based on the max−dmin and P-OSM precoders which require the knowledge of the channel state information (CSI) at transmitter. To make the use of the CSI realistic in WSN, we quantized these two precoders. The idea is to reduce the information sent on the feedback channel while still having a good performance of the precoders. We used some techniques from the literature and proposed others to perform this quantization. We then proposed various energy-efficient cooperative schemes that allow the implementation of max−dmin and P-OSM precoders with a quantized feedback channel. Performances of the proposed schemes in terms of energy consumption and transmission delay are evaluated and analyzed by comparing them with the space-time block codes (STBC) based cooperative scheme used in literature. Results show that our proposed systems provide more energy savings than the STBC one even in the presence of synchronization errors between the sensors. We are further interested in the application of sensor networks in high-voltage substations in the context of the Smart Grid. The objective is to evaluate the performance of proposed cooperative systems in the presence of impulsive noise and in a real environment of high-voltage substation in Quebec. By using measured data of impulsive noise obtained from the Ecole de Technologie Supérieure of Montreal, we determined a statistical model of the impulsive noise. In order to use the multi-antenna system, we propose an extension of this model.