Études des systèmes de communications sans-fil dans un environnement rural difficile

Les systèmes de communication sans fil, ayant de nombreux avantages pour les zones rurales, peuvent aider la population à bien s'y établir au lieu de déménager vers les centres urbains, accentuant ainsi les problèmes d’embouteillage, de pollution et d’habitation. Pour une planification et un déploiement efficace de ces systèmes, l'atténuation du signal radio et la réussite des liens d’accès doivent être envisagées. Ce travail s’intéresse à la provision d’accès Internet sans fil dans le contexte rural canadien caractérisé par sa végétation dense et ses variations climatiques extrêmes vu que les solutions existantes sont plus concentrées sur les zones urbaines. Pour cela, nous étudions plusieurs cas d’environnements difficiles affectant les performances des systèmes de communication. Ensuite, nous comparons les systèmes de communication sans fil les plus connus. Le réseau sans fil fixe utilisant le Wi-Fi ayant l’option de longue portée est choisi pour fournir les communications aux zones rurales. De plus, nous évaluons l'atténuation du signal radio, car les modèles existants sont conçus, en majorité, pour les technologies mobiles en zones urbaines. Puis, nous concevons un nouveau modèle empirique pour les pertes de propagation. Des approches utilisant l’apprentissage automatique sont ensuite proposées, afin de prédire le succès des liens sans fil, d’optimiser le choix des points d'accès et d’établir les limites de validité des paramètres des liens sans fil fiables. Les solutions proposées font preuve de précision (jusqu’à 94 % et 8 dB RMSE) et de simplicité, tout en considérant une multitude de paramètres difficiles à prendre en compte tous ensemble avec les solutions classiques existantes. Les approches proposées requièrent des données fiables qui sont généralement difficiles à acquérir. Dans notre cas, les données de DIGICOM, un fournisseur Internet sans fil en zone rurale canadien, sont utilisées. Wireless communication systems have many advantages for rural areas, as they can help people settle comfortably and conveniently in these regions instead of relocating to urban centers causing various overcrowding, habitation, and pollution problems. For effective planning and deployment of these technologies, the attenuation of the radio signal and the success of radio links must be precisely predicted. This work examines the provision of wireless internet access in the Canadian rural context, characterized by its dense vegetation and its extreme climatic variations, since existing solutions are more focused on urban areas. Hence, we study several cases of difficult environments affecting the performances of communication systems. Then, we compare the best-known wireless communication systems. The fixed wireless network using Wi-Fi, having the long-range option, is chosen to provide wireless access to rural areas. Moreover, we evaluate the attenuation of the radio signal, since the existing path loss models are generally designed for mobile technologies in urban areas. Then, we design a new path loss empirical model. Several approaches are then proposed by using machine learning to predict the success of wireless links, optimize the choice of access points and establish the validity limits for the pertinent parameters of reliable wireless connections. The proposed solutions are characterized by their accuracy (up to 94% and 8 dB RMSE) and simplicity while considering a wide range of parameters that are difficult to consider all together with conventional solutions. These approaches require reliable data, which is generally difficult to acquire. In our case, the dataset from DIGICOM, a rural Canadian wireless internet service provider, is used

Extended WIFI network design model for ubiquitous emergency events

Telecommunication is the exchange of information and data over significant distance by electronic means. During extreme events such as natural disasters and urgent events it becomes more and more important to preserve the communication devices and infrastructure to exchange information between rescue teams and persons in damaged zone based on their area. When extreme event happens, many communication scenarios can be considered. We focus on a the case of destruction of traditional communication networks during an emergency event such as natural disasters in which it is important to find an alternative network architecture to prevent the death and injury of thousands of people. The rescue teams are unable to locate and communicate with victims on right time. This work presents network architectural design model to extend the range of WIFI networks and help people access to Internet or get rescue when the damage affects the most existing telecommunication networks. This model is validated by analyzing two communication scenarios

Survey of health care context models : prototyping of healthcare context framework

HealthCare system is considered a key element in ubiquitous computing, which means health care services are recommended at any time and at any places to monitor patients based on their context. This study aims to define a simple framework that could be guidelines when you start thinking about building a health context-awareness system in ubiquitous environment. This paper starts by defining the concept of context and then presenting a comprehensive list of context models. Outcome of the work of this research is an ontology healthcare model based on current context of patient which makes monitoring process more accurate. This study includes an Android application in order to prove the concept of this hypothesis

Case studies of communications systems during harsh environments: A review of approaches, weaknesses, and limitations to improve quality of service

The failure of communications systems may cause catastrophic damage to human life and economic activities as people are unable to communicate with each other in a timely manner and with a convenient quality of service. Therefore, the exchange of information is more than necessary for people in their everyday life or during harsh environments to prevent the death and injury of thousands of individuals. The study of communications systems behavior in harsh environments helps to design or select more resilient technologies that are capable of operating in challenging conditions. This article reviews existing approaches, major causes of failure, and weaknesses of communications systems during extreme events. First, we highlight the importance of communications systems, and then we examine related works, how communication may fail, and the effect of this failure on human life in general and during extreme events response. Furthermore, we study and analyze how communications are used during various stages of extreme events, and we identify the main weaknesses and limitations that communications systems may suffer based on many case studies. To conclude, we identify and discuss relevant attributes, requirements, and recommendations for communications systems to perform with a suitable quality of service during harsh environments and to reduce risks of communication failure in challenging conditions

Challenges and requirements for communication technologies in connected zones

With the emergence of communication technologies (CT), humans have become more connected than ever to their environment through various devices and computer platforms. These devices are integrated into everyday life, in an omnipresent way, such that people can interact effortlessly and intuitively. The goal is to improve their life by allowing them access to various services and information at any time and in any situation or place they are even in harsh environment. This intensive technological presence in an area is called smart or connected zones. Within these zones, technology is used to collect, process and share information in order to facilitate citizens’ activities and assist authorities in decision-making and efficient service provision. This paper reviews principal requirements and challenges for CT to be used in such zone. First, we introduce its concept by highlighting its characteristics, features, devices and applications. Then we examine related works, communication requirements and challenges. We finish this paper by the conclusion

WiFi coverage range characterization for smart space applications

Recently, humans are more and more dependent to communication technologies (CT) in their everyday life to get services, exchange information and communicate with their relatives. Hence, many researches have been made in order to propose convenient and low-cost solutions compatible with the context of smart spaces. This paper characterizes the range of WiFi for outdoor applications in comparison with most known empirical path loss models, and analyzes its impact for smart space services like Internet of Things (IoT). The obtained range is 550m tested with a Samsung Galaxy S5 smartphone, and the comparison with empirical model showed a good difference. Hence the validity and accuracy of those models will be examined for this context, in order to develop an empirical model taking into account environmental effect during our future research. As solutions based on WiFi are generally low cost, its technical characteristics are illustrated and a wide deployment scenario based on this technology is explained on light of obtained results

An accurate empirical path loss model for heterogeneous fixed wireless networks below 5.8 GHz frequencies

Great progress has been made in providing convenient wireless communications with easy connectivity for users everywhere. Many empirical path loss (PL) models have been developed to assess the performance of new radio networks. This article first studies the state-of-the-art of empirical PL models, along with vegetation effects on radio signal propagation. Next, an accurate empirical PL model is proposed for fixed wireless networks under challenging rural propagation conditions. The proposed model is based on a Canadian dataset from a wireless internet service provider, using the Wireless-To-The-Home technology in the unlicensed 900 MHz, 2.4 and 5.8 GHz ISM bands and in the licensed 3.65 GHz band. The proposed model considers several parameters, such as line-of-sight obstructions, frequency bands and dynamic link distance splitting, in addition to seasonal variations in PL attenuation. It outperforms other models in terms of accuracy when tested on a dataset from a different Canadian region, and it provides excellent and steady accuracy when tested on a largely different open-access dataset for mobile communication technology from seven different regions in England