Daniela Dragomirescu

Simulation Platform for Wireless Sensor Networks Based on Impulse Radio Ultra Wide Band

Impulse Radio Ultra Wide Band (IR-UWB) is a promising technology to address Wireless Sensor Network (WSN) constraints. However, existing network simulation tools do not provide a complete WSN simulation architecture, with the IR-UWB specificities at the PHYsical (PHY) and the Medium Access Control(MAC) layers. In this paper, we propose a WSN simulation architecture based on the IR-UWB technique. At the PHY layer, we take into account the pulse collision by dealing with the pulse propagation delay. We also modelled MAC protocols specific to IRUWB,for WSN applications. To completely fit the WSN simulation requirements, we propose a generic and reusable sensor and sensing channel model. Most of the WSN application performances can be evaluated thanks to the proposed simulation architecture. The proposed models are implemented on a scalable and well known network simulator: Global Mobile Information System Simulator (GloMoSim). However,they can be reused for all other packet based simulation platforms.

Miniaturized Wireless Sensor Networks

This paper addresses an overview of the wireless sensor networks. It is shown that MEMS/NEMS technologies and SIP concept are well suited for advanced architectures. It is also shown analog architectures have to be compatible with digital signal techniques to develop smart network of microsystem

60GHz wireless nano-sensors network for structure health monitoring as enabler for safer, greener aircrafts

The deployment of Wireless Sensors Network for Structure Health Monitoring will allow better maintenance of the aircraft and predictive diagnosis of the aircrafts in a long term approach. This paper presents our research on the design of wireless communicating nano-objects for Structure Health Monitoring in the aircrafts and the improvements bring by the nanotechnologies. The main challenges we address here are the design of ultra low power communicating circuits to enable high lifetime for the communicating nodes and their integration on flexible substrate to allow their deployment in difficult accessible places on the aircraft using conventional technologies. Other main issues are the choice of the communicating frequency which will allow a high number of communicating nodes in such a small area like the cabin of an aircraft and the choice of the network architecture.

System architecture modeling of an UWB receiver for wireless sensor network

This paper presents a method for system architecture modeling of an IR-UWB (Impulse Radio Ultra WideBand) receiver for sensors networks applications. We expose the way for designing an FPGA (Field Programmable Gate Array) receiver starting from a previous study based on system modeling on Matlab. The proposed receiver architecture is first designed and validated on Matlab, before being implemented, thanks to VHDL language, on a FPGA. Our study shows the interest and the advantages of co-design Matlab-VHDL. We will propose here different IR-UWB receiver architecture depending on the modulation used. We will also introduce in this paper a data-rate and TH-code reconfigurable receiver. Using co-simulation Matlab-VHDL, we have compared three kind of IR-UWB receiver: TH-PPM, TH-OOK, TH-BPAM, with respect to BER/SNR criteria and in the specific context of wireless sensors networks, at high level (Matlab) and hardware level (FPGA-Xilinx).

An ultra small passive balun for 60 GHz applications in CMOS 65nm technology

In this paper a novel method to design a miniaturized Marchand Balun is proposed. The main issue in the balun design is to limit its physical dimensions. This work shows a device that achieves good performance, in terms of phase and amplitude balance, and at the same time reduced size. To allow such a result, an accurate analysis of the coupling phenomena was done. The principal equations that characterize the structure are summarized in the paper. The device is fabricated in 65 nm CMOS technology. The balun has been designed for application in a wide band low power 60 GHz transceiver.

Nonlinear behavioral modeling of oscillators in VHDL-AMS using Artificial Neural Networks

In this paper an approach to behavioral modeling of microwave oscillators is described. The presented model takes into account start-up, steady state behavior and phase noise. To describe the nonlinearities, an artificial neural network (ANN) is employed. The dynamic behavior of the oscillator is described by a system of differential equations that are solved in VHDL-AMS. As opposed to input-output models of microwave devices, this paper presents a self sustaining oscillation, which starts from a small injected excitation (e.g. noise) and ends in a stable limit cycle. Additionally, the phase noise characteristics of the oscillator in the 1/f2 and flat region are emulated.

A new approach to RF MEMS shunt switch modeling from K-band up to W-band

In this paper, we present a new approach to RF MEMS shunt switch modeling from K-band up to W-band. The switch model is based on a size parameter that allows to scale the models for different frequencies.

Low power digital TTL command for 1bit 60GHz RF MEMS phase shifter

This paper presents a circuit used to actuate Radio Frequency MicroElectroMechanical Systems (RF MEMS) based phase shifters for 60GHz beam forming. Wireless transmission in the 60GHz band show a dramatic free space loss, thus making it mandatory to use antennas with high gain in a desired direction. Beam forming is then necessary to optimize the link budget between communicating nodes. Antenna arrays can be used for beam forming. The work done at LAAS was aiming to provide RF MEMS based phase shifters working with a standard digital command. RF MEMS commonly have high actuation voltages usually obtained with charge pumps. This paper presents a full 1bit phase shifter with a digital translation part, an analog DC-DC converter, and an RF MEMS based loaded line phase shifter for 60GHz signals. This converter is built using boost converters as an alternative to the use of charge pumps for driving RF MEMS in the field of wireless communications. Boost converters, despite relatively high current peaks, allow shorter settling times compared to charge pumps.

3D heterogeneous integration of wireless communicating nano-sensors on flexible substrate

In this communication, the 3D heterogeneous integration of miniaturized communicating modules used for wireless network application is described. These communicating objects present the particularity of being in Nano-scale range. In fact, each object is composed of Nano-sensors, transceivers and E/R antenna. Such investigated ways of Nano-system integration will allow the development of sensor communicating modules which can be inserted and located in areas with access difficulty (in particular in non planar area) or even in inaccessible places. This attractive integration concept is discussed and illustrated here.

SOPC Co-design Platform for UWB System in Wireless Sensor Network Context

This paper presents our approach of the radio interface problematic for wireless sensor network. We introduce the WSN context and constraints associated. We propose an IR-UWB solution and illustrate why it could be a viable solution for WSN. A high level modelling and simulation platform for IR-UWB radio interface is proposed on Matlab. It allows us to determine according to BER versus Eb/N0 criteria and the WSN constraints what kind of design is more adequate. Moreover, a co-design co-simulation platform Matlab VHDL is proposed here. Using this platform we designed IR-UWB transceiver having reconfigurable capabilities, such as data rate reconfiguration, time hopping code, spectrum occupation and radio range reconfiguration.