Recent IoT Communication Systems. Towards reliable, sustainable and maintainable smart cities
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Over the past few decades, there has been a dramatic and unprecedented growth of populations in the cities. Statistics show that today’s numbers are expected to increase exponentially over the next 30 years. In order to help managing the needs of the city residents, cities are moving towards utilizing advanced technologies and networks. Nowadays, there has been a growing interest in the Internet of Things (IoT) technology attempting to solve traditional challenges that most of cities over the world are facing. In fact, the IoT is a revolutionary technological advancement that can dramatically transform cities in various ways from improving public safety to making them smarter. In this context, IoT-based smart city, will be able to efficiently manage and maintain its infrastructures, thereby reducing operating costs and improving the life of its residents. However, the optimal growth of IoT-based smart city concept will necessarily depend on the existing and emerging IoT technologies. Thus, there is a need to investigate new and emerging technologies. In this thesis, a recent IoT wireless communication system for IoT-based smart city use is investigated. Owing to its efficiency in IoT applications in terms of low-power and wireless connectivity, IQRF (Intelligent Connectivity using Radio Frequency) technology appears to be one of the reasonable IoT and Wireless Sensor Network (WSN) technologies in the commercial market. Recently, IQRF has emerged as a promising technology for the IoT and WSN as a support to short- and medium-range low-power existing IoT technologies by providing reasonable range and cost-effective solutions. As in the case of most IoT and WSNs technologies, the deployment of IQRF networks requires the study of its radio propagation characteristics. On the other hand, WSNs usually use sensor nodes placed in open, public or remote areas and in large numbers as dictated by the concept of IoT. However, the requirements for the large-scale deployment of the these type of networks are rapidly increasing with a major security concern. Therefore, the security aspects of IQRF technology need to be studied as well. The present thesis, through the paperwork carried out, is devoted mainly to the study of the propagation characteristics and security aspects of IQRF technology. To begin, a review study describing smart city architecture along with the main challenges facing IoT-based smart city concept is conducted. Moreover, popular cost-effective wireless IoT technologies comparable to IQRF technology are briefly introduced. In this study, the benefits of IQRF technology over other introduced technologies are discussed by performing theoretical comparison based on technical documentation and reports. Moreover, three use-cases of IoT-based smart city using IQRF technology are conceptually presented. The three use-cases were part of the research efforts being undertaken by NTNU on the development of Gjøvik Municipality in Norway as IoT-based smart city. For IQRF radio propagation characteristics study, the communication channel of IQRF transceivers (TRs) in outdoor and indoor environments is investigated. For this purpose, two types of IQRF TRs are used during the whole study. The difference between TRs resides in the type of the antenna used on each TR. One type contains a Meander Line Antenna (MLA) etched on the Printed Circuit Board (PCB) of the TR itself while the other type has a connector in order to connect an external Straight-Line Dipole Antenna (SLDA). Real world deployment of IQRF-based WSNs in different environments requires accurate path loss modeling to estimate the network coverage and other link performances. Hence, for outdoor environment, measurement campaigns of Received Signal Strength Indicator (RSSI) were conducted outdoor in an urban area for Line-of-Sight (LoS) and Non-Line-of-Sight (NLoS) scenarios. From the measurements, empirical path loss models are calculated and proposed for the deployment of IQRF networks. In order to evaluate the prediction accuracy of well-known empirical path loss models for urban environment such as COST-231, Walfisch–Ikegami and COST-231 Hata, the measurements are compared with the predicted path loss values. On the other hand, for indoor environment, preliminary propagation measurements are conducted using IQRF TRs. The measurements are conducted in a single corridor of a building in LoS link and two perpendicular corridors in NLoS link with one single knife-edge. Moreover, the measured path loss values are compared with the predicted path loss values in order to comparatively assess the prediction accuracy of the well-known empirical models established in indoor environment such as ITU-R P.1238-9 and WINNER II. For the security aspects of the IQRF technology, the study is performed in two phases. In the first phase, a comprehensive survey is conducted focusing on the security mechanisms used in the most prominent IoT standards and technologies. In this survey, an IoT ecosystem is define from the core technologies view point. Then, a modified three-layer IoT architecture is propose by dividing the perception layer into elementary blocks based on their attributed functions. The proposed architecture serves as a framework to classify the introduced IoT technologies and standards. IoT enabling technologies, potential attacks, and security countermeasures are also presented in the survey and classified un der each layer of the proposed architecture. Among the IoT technologies presented in this survey, a special interest is given to IQRF technology by highlighting the security mechanisms employed in this technology. In the second phase, IQRF is introduced as Low-PowerWide Area Network (LPWAN) technology. Using IQRF devices in such networks are expected to be the targets of cyber threats. This is due to the fact that most of the LPWAN technologies use simple cryptographic methods that make them vulnerable to various security and privacy threats. In this direction, a preliminary cybersecurity study of IQRF technology is being conducted. It has been found that one reasonable way to study the security aspects of IQRF is to apply risk assessment methods in order to analyze risks that could represent potential vulnerabilities in the system before deploying IQRF networks. In this context, security risk analysis is performed on IQRF technology using Failure Mode Effects Analysis (FMEA) approach. With the help of this approach, security risks in IQRF technology are identified, and further actions that can be used to prevent IQRF networks from being exposed to cyber attacks are proposed. Finally, it is believed that the findings presented in this thesis could offer useful insights for researchers and developers interested in the development of IoT-based smart city applications.