Gheorghe Zaharia

Wideband and dynamic characterization of the 60GHZ indoor radio propagation — future homeWLAN architectures

This paper presents some results of a study concerning the radio propagation at 60GHZ in residential environments performed by theIETR (Electronic and Telecommunication Institute of Rennes, France). This study is part of aRNTR project named “COMMINDOR”. This exploratory project concerns the very high data rate (155 Mbit/s) and small range (about 10 m) radio communication systems for future home networks, which will permit multimedia equipment interconnection and control.The study is based on several measurement campaigns realized with a channel sounder based on the sliding correlation technique. This channel sounder has a 500MhZ bandwidth and a 2.3 ns effective time resolution. The measurements have been performed in residential furnished environments. The study of the angles-of-arrival (AOA) emphases the importance of openings (such as doors, staircase, etc.) for the radio propagation between adjacent rooms. A particular attention is paid to the influence of human activity on radio propagation. It is shown that people movements can make the propagation channel unavailable during about one second. From the characterization study of the indoor radio propagation, several recommendations concerning the deployment of the very high data rate 60GHZ wireless networks are derived.RésuméCet article présente une partie des résultats de la caractérisation de la propagation radioélectrique à 60GHZ en environnement résidentiel, menée par l’IETR. Cette étude s’inscrit dans le cadre du projetRNTR intitulé «OMMINDOR». Ce project exploratoire s’intéresse aux systèmes de radiocommunications à très haut débit (155 Mbit/s) et courte portée (dizaine de mètres) pour les futurs réseaux domestiques, permettant l’interconnexion et le contrôle d’équipements multimédias grand public.L’étude repose sur des campagnes de mesures effectuées avec un sondeur de canal utilisant la technique du corrélateur glissant, ayant une bande d’analyse de 500MhZ et une résolution temporelle effective de 2,3 ns. Les mesures se sont déroulées dans des environnements résidentiels meublés. L’étude des angles d’arrivée des ondes souligne le rôle des ouvertures (telles que les portes, les escaliers, etc.) dans la propagation entre pièces. Une attention particulière est accordée à l’influence de l’activité humaine sur la propagation. Il en ressort que les déplacements des personnes peuvent rendre le canal indisponible pour des durées de l’ordre de la seconde. À partir de la caractérisation du canal de propagation, plusieurs recommandations concernant le déploiement de réseaux sans fil à très haut débit à 60 GHz en milieu résidentiel sont proposées.

Hardware Simulator for MIMO Radio Channels: Design and Features of the Digital Block

This paper presents the realization of the digital block of a hardware simulator of MIMO propagation channels for UMTS and WLAN applications. The hardware simulator must reproduce the behavior of the radio propagation channel, thus making it possible to test on table the mobile radio equipments. The advantages are: low cost, short test duration, possibility to ensure the same test conditions in order to compare the performance of various equipments. After the presentation of the general characteristics of the hardware simulator, an architecture of the digital block is proposed and its accuracy is analyzed.

ZigBee-based sensor network for shipboard environments

This paper studies the feasibility of deploying a ZigBee-based sensor network aboard ships. The objective is to verify if this network can be a suitable alternative of the actual shipboard wired monitoring system. Therefore, measurements campaigns have been conducted to evaluate the quality of ZigBee point-to-point communications aboard a ferry operating in the sea. Different configurations and environments were studied on each deck of the ferry. Experiments during the ship operation have been conducted to take into account the influence of crews and passengers movements, engines and machines on the quality of wireless transmission. In a second time, a full scale wireless sensor network was deployed aboard another ferry. Real time data such as temperature, humidity and pressure were sent from different ferry decks to a central base station located in the control room. This network has shown a very good connectivity, regardless of the metallic shipboard environments.

Design of the Digital Block of a Hardware Simulator for MIMO Radio Channels

The aim of the regional research project SIMPAA2, which continues the former national research SIMPAA project, is the realization of a hardware simulator of MIMO propagation channels for UMTS and WLAN applications. The simulator must reproduce the behavior of the radio propagation channel, thus making it possible to test on table the mobile radio equipments. The advantages are: low cost, short test duration, possibility to ensure the same test conditions in order to compare the performance of various equipments

Digital block design of MIMO hardware simulator for LTE applications

This paper presents new frequency domain and time domain architectures for the digital block of a hardware simulator of MIMO propagation channels, with 3GPP TR 36.803 channel models test, for LTE applications. The hardware simulator facilitates the test and validation cycles by replicating channel artifacts in a controllable and repeatable laboratory environment, thus making it possible to ensure the same test conditions in order to compare the performance of various equipments. After the description of the general characteristics of the hardware simulator, the new architectures of the digital block are presented and designed on a Xilinx Virtex-IV FPGA. Their accuracy and latency are analyzed. 3GPP TR 36.803 channel models test are given in details.

Touch-less heartbeat detection and cardiopulmonary modeling

This paper presents a contact-less heartbeat detection system and a cardiopulmonary modeling. Using a vector network analyzer, our proposed microwave system shows the ability of detecting the heartbeat signal at different frequencies, as well as at different output power levels. Based on parameters extracted from real measurements, a model representing the heartbeat and the respiration signals is presented. Different processing techniques are used in order to separate the heartbeat and the respiration signals. For different signal to noise ratios, wavelet filters show higher accuracy over classic filters in determining both the heartbeat rate and the heart rate variability.

Improved frequency domain architecture for the digital block of a hardware simulator for MIMO radio channels

This paper presents a new frequency domain architecture for the digital block of a hardware simulator of MIMO propagation channels. This simulator can be used for UMTS and WLAN applications in indoor and outdoor environments. A hardware simulator must reproduce the behavior of the radio propagation channel, thus making it possible to test “on table” the mobile radio equipments. The advantages are: low cost, short test duration, possibility to ensure the same test conditions in order to compare the performance of various equipments. After the presentation of the general characteristics of the hardware simulator, the new architecture of the digital block is presented and designed on a Xilinx Virtex-IV FPGA, and its accuracy is analyzed.

Cooperative communications between vehicles and intelligent road signs

CAPTIV is a research program proposing new low-cost and energy-efficient mobile communications solutions to ease and make safer road traffic conditions. Considering ¿intelligent¿ road signs and vehicles, i.e. equipped with an autonomous radio communication system, drivers will be able to receive at any time various information about traffic fluidity or road sign identification. In order to reduce deployment cost and increase lifetime of the whole system, Multi-Input Multi-Output (MIMO) signal processing techniques are used. Considering each crossroads as a communication node, the possible cooperation between road signs allows energy-efficient communications between crossroads. MIMO channels characterization and modeling, specific antennas conception, associated with signal processing techniques allow to further optimize the energy consumption between nodes. A driving simulator is used in order to both validate the communication system and protocols between vehicles and road signs and evaluate the effect of the additional information on the driver behavior. Supported by the Brittany Regional Council, CAPTIV is a highly applicative program. A first prototype of such a communicating crossroads will be presented in the Vehipole in Saint-Brieuc (technological site devoted to ITS experimentations).

Influence of the human activity on the propagation characteristics of 60 GHz indoor channels

The 60 GHz frequency band appears to be very promising for wireless multimedia services in the next years. The 60 GHz propagation channel has to be accurately characterized for an appropriate design of high data rate systems (>100Mb/s). In this paper, our interest is to be determine the influence of the human activity on the propagation characteristics at 60 GHz. This influence is hardly ever taking into account in the published studies on the 60 GHz channel characterization. However, the human activity is a determining factor at millimeter-waves. Channel sounding campaigns have been conducted. The measurement results highlight the strong disruptions caused by a person shadowing the direct path between two antennas. These disruptions make the channel unavailable for durations greater than 100 ms. Long-term measurements are analyzed in order to evaluate the unavailability rate of 60 GHz radio links. From these results, some solutions are suggested in order to reduce the shadowing problems.

Performance analysis of a hierarchical shipboard Wireless Sensor Network

Wireless Sensor Networks (WSN) have recently gained a great attention in several applications such as environmental monitoring and target tracking. Applying this technology to shipboard monitoring systems may be a cost-effective solution to reduce the cost of wires installation and maintenance. However, wireless communications on board ships may be severely obstructed by the metallic structure of bulkheads. In this paper, we analyze the efficiency of a shipboard WSN by measurement and simulation. A measurement campaign is conducted to study the radio wave propagation and to verify the feasibility of a WSN on board a ship. Based on the measurement results, a hierarchical group-based topology for a large-scale shipboard WSN is proposed. A realistic simulation model of the ship, taking into account the environment particularities, is then performed using OPNET network simulator. Performance of the WSN architecture is evaluated using the ZigBee model. Measurement results show the feasibility of WSN technology on board ships, while simulation results show significant performance of proposed architecture in terms of end-to-end delay and packet delivery ratio.