Positioning based information technique in cooperative MIMO-OFDM systems

International audienceFuture Communication networks are tending towards a diverse wireless networking world where the positioning information (PI) could be helpful in different techniques like the dynamic resource allocation. On the other hand, the PI could be widely used for cooperative techniques in the relay and/or routing selection process. In this paper, we propose to use the PI in the selection of the relays and then to apply an efficient double layer distributed space time block code (DLSTBC) scheme between the different relays. Using the amplify and forward (AF) technique, we show that the proposed code is very efficient whatever the transmitted power is. Moreover, we show that the relay selection process based on PI yields very powerful results when compared to the random relay selection (RS) proces

MIMO Hardware Simulator Using Standard Channel Models and Measurement Data at 2.2 and 3.5 GHz

20 pagesInternational audienceA wireless communication system can be tested either in actual conditions or by using a hardware simulator reproducing actual conditions. With a hardware simulator it is possible to freely simulate a desired type of a radio channel. This paper presents architectures for the digital block of a hardware simulator of MIMO (multiple-input multiple-output) propagation channels. This simulator can be used for LTE (long term evolution system) and WLAN (wireless local area networks) 802.11ac applications, in indoor and outdoor environments. The first architecture is appropriate for shipboard environments, while the second corresponds to outdoor-to-indoor environments and considers the wave propagation penetration within buildings. Measurements campaigns carried out at 2.2 and 3.5 GHz have been conducted to obtain the impulse responses of the channel using a MIMO channel sounder designed at IETR. The measurements are processed with an algorithm extracting the dominant paths. The architectures of the digital block are implemented on a Xilinx Virtex-IV FPGA (field programmable gate array). After the implementation of the impulse responses, the accuracy, the occupation on the FPGA and the latency of the architectures are analyzed

Hardware Simulator Design for MIMO Propagation Channel on Shipboard at 2.2 GHz

27 pagesInternational audienceA wireless communication system can be tested either in actual conditions or with a hardware simulator reproducing actual conditions. With a hardware simulator it is possible to freely simulate a desired radio channel, making it possible to test "on table" mobile radio equipments. This paper presents new architectures for the digital block of a hardware simulator ofMIMO propagation channels. This simulator can be used for LTE and WLAN IEEE 802.11ac applications, in indoor and outdoor environments. However, in this paper, specific architectures of the digital block of the simulator for shipboard environment are presented. A hardware simulator must reproduce the behavior of the radio propagation channel. Thus, ameasurements campaign has been conducted to obtain the impulse responses of the shipboard channel using a channel sounder designed and realized at IETR. After the presentation of the channel sounder, the channel impulse responses are described and implemented. Then, the new architectures of the digital block of the hardware simulator, implemented on a Xilinx Virtex-IV FPGA are presented. The accuracy, the occupation on the FPGA and the latency of the architectures are analyzed

Wireless Sensor Network on Board Vessels

International audienceWireless Sensor Networks (WSNs) have been used recently in different applications such as environmental monitoring and target tracking. Few papers have investigated the viability of this technology on board ships. We study in this paper the possibility of replacing the wired shipboard monitoring system by a WSN. This environment has a specific metallic structure which makes the wireless communication more difficult than in other classical indoor and outdoor environments. Two types of experiments have been carried out on board a ferry-type boat during sailings and stopovers. The first experiment consists of point-to-point measurements using ZigBee-based equipments and the second one consists of deploying and testing a WSN on board the ferry. These tests have been conducted during realistic conditions on board the ferry, which give a high level of reliability to results with respect to the earlier experiments on board ships moored to the harbor. In spite of the harsh metallic structure and the dynamic environments on board the ferry, the obtained results have shown that the wireless solution may be a cost-effective alternative of the huge amount of cables used actually to connect sensors to central control units

Performance Analysis of a Hierarchical Shipboard Wireless Sensor Network

International audienceWireless 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

Étude de la propagation des ondes électromagnétiques pour le déploiement des réseaux sans fil à bord d'un bateau

International audienceAfin de déployer des réseaux de communications sans fil (réseau local sans fil, réseau de capteurs, téléphone sans fil) à bord des navires, une étude de la propagation des ondes électromagnétiques (EM) est nécessaire dans cet environnement particulier. En effet, les communications sans fil à l'intérieur d'un bateau peuvent être sévèrement limitées par la structure métallique des ponts, des cloisons et des portes étanches. Cet article présente une étude expérimentale de la propagation des ondes EM à bord des navires. Ce travail fait partie du projet SAPHIR financé par la région Bretagne. Des mesures en porteuse pure, visant à déterminer la couverture radioélectrique pour des environnements typiques, ont été réalisées à bord d'un ferry. Ensuite, d'autres mesures, consistant en une caractérisation doublement directionnelle du canal de propagation en utilisant un sondeur MIMO (Multiple Input Multiple Output), ont été réalisées. Les mesures MIMO visent à déterminer les principales directions de propagation des ondes EM dans des scénarios typiques, tels que la communication entre des pièces adjacentes, les ponts adjacents, ou entre les cabines des passagers et les couloirs

Characterization, modeling and simulation of the MIMO propagation channel

International audienceThis article deals with several aspects relative to the MIMO propagation channel. Based on simulations and/or measurements, different approaches are used to model the propagation channel. These models are useful for the MIMO system design. Several studies are performed in order to realize realistic simulation of MIMO channel. Different measurement techniques are used in characterizing the propagation channel in various environments. Measurement campaigns made in different situations have been analyzed to obtain the relevant statistical parameters of the channel. Simulation of MIMO channel is then presented. Measurement and simulation results provide an evaluation of the capacity of MIMO channel. Obtained results show feasibility in the integration of MIMO techniques in practical wireless communication systems.Cet article traite de plusieurs aspects relatifs au canal de propagation MIMO. Différentes approches, basées sur des simulations et des mesures, utilisées pour modéliser le canal sont d’abord présentées. Ensuite, les différentes techniques de mesure utilisées dans le but de caractériser le canal de propagation dans divers milieux sont décrites. Des campagnes de mesures effectuées dans différents environnements sont analysées pour obtenir les paramètres statistiques du canal. Quelques problématiques liées à la simulation du canal MIMO sont évoquées notamment en lien avec une simulation réaliste dans des milieux complexes. Les résultats obtenus, en simulation comme en mesure, permettent une évaluation de la capacité du canal MIMO. Ces résultats permettent de discuter de l’intégration des techniques MIMO dans des systèmes de communication sans fil

Mortality and pulmonary complications in patients undergoing surgery with perioperative SARS-CoV-2 infection: an international cohort study

Background: The impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on postoperative recovery needs to be understood to inform clinical decision making during and after the COVID-19 pandemic. This study reports 30-day mortality and pulmonary complication rates in patients with perioperative SARS-CoV-2 infection. Methods: This international, multicentre, cohort study at 235 hospitals in 24 countries included all patients undergoing surgery who had SARS-CoV-2 infection confirmed within 7 days before or 30 days after surgery. The primary outcome measure was 30-day postoperative mortality and was assessed in all enrolled patients. The main secondary outcome measure was pulmonary complications, defined as pneumonia, acute respiratory distress syndrome, or unexpected postoperative ventilation. Findings: This analysis includes 1128 patients who had surgery between Jan 1 and March 31, 2020, of whom 835 (74·0%) had emergency surgery and 280 (24·8%) had elective surgery. SARS-CoV-2 infection was confirmed preoperatively in 294 (26·1%) patients. 30-day mortality was 23·8% (268 of 1128). Pulmonary complications occurred in 577 (51·2%) of 1128 patients; 30-day mortality in these patients was 38·0% (219 of 577), accounting for 81·7% (219 of 268) of all deaths. In adjusted analyses, 30-day mortality was associated with male sex (odds ratio 1·75 [95% CI 1·28–2·40], p\textless0·0001), age 70 years or older versus younger than 70 years (2·30 [1·65–3·22], p\textless0·0001), American Society of Anesthesiologists grades 3–5 versus grades 1–2 (2·35 [1·57–3·53], p\textless0·0001), malignant versus benign or obstetric diagnosis (1·55 [1·01–2·39], p=0·046), emergency versus elective surgery (1·67 [1·06–2·63], p=0·026), and major versus minor surgery (1·52 [1·01–2·31], p=0·047). Interpretation: Postoperative pulmonary complications occur in half of patients with perioperative SARS-CoV-2 infection and are associated with high mortality. Thresholds for surgery during the COVID-19 pandemic should be higher than during normal practice, particularly in men aged 70 years and older. Consideration should be given for postponing non-urgent procedures and promoting non-operative treatment to delay or avoid the need for surgery. Funding: National Institute for Health Research (NIHR), Association of Coloproctology of Great Britain and Ireland, Bowel and Cancer Research, Bowel Disease Research Foundation, Association of Upper Gastrointestinal Surgeons, British Association of Surgical Oncology, British Gynaecological Cancer Society, European Society of Coloproctology, NIHR Academy, Sarcoma UK, Vascular Society for Great Britain and Ireland, and Yorkshire Cancer Research

Antenna arrays design and calibration for high resolution MIMO channel sounding at 3.5 GHz

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