Vehicle as a Service (VaaS): Leverage Vehicles to Build Service Networks and Capabilities for Smart Cities

Smart cities demand resources for rich immersive sensing, ubiquitous communications, powerful computing, large storage, and high intelligence (SCCSI) to support various kinds of applications, such as public safety, connected and autonomous driving, smart and connected health, and smart living. At the same time, it is widely recognized that vehicles such as autonomous cars, equipped with significantly powerful SCCSI capabilities, will become ubiquitous in future smart cities. By observing the convergence of these two trends, this article advocates the use of vehicles to build a cost-effective service network, called the Vehicle as a Service (VaaS) paradigm, where vehicles empowered with SCCSI capability form a web of mobile servers and communicators to provide SCCSI services in smart cities. Towards this direction, we first examine the potential use cases in smart cities and possible upgrades required for the transition from traditional vehicular ad hoc networks (VANETs) to VaaS. Then, we will introduce the system architecture of the VaaS paradigm and discuss how it can provide SCCSI services in future smart cities, respectively. At last, we identify the open problems of this paradigm and future research directions, including architectural design, service provisioning, incentive design, and security & privacy. We expect that this paper paves the way towards developing a cost-effective and sustainable approach for building smart cities.Comment: 32 pages, 11 figure

Performance Analysis of Train Communication Systems

Trains are considered as a highly efficient transport mode which generate significant challenges in terms of their communication systems. For improved safety, to cope with the expected rapid increase in traffic, and to meet customer demands, an enhanced and reliable communication system is required for high-speed trains (HSRs). Mobile phone and laptop users would like to make use of the non-negligible time that they spend commuting but current HSR communication systems have a foreseeable end to their lifetime and a reliable, efficient, and fast communication replacement system has become essential. Encouraged by the use of existing power line networks for communication purposes, this research investigates the possibility of developing a train communication system based on the use of overhead line equipment (OLE). The ABCD transfer line model is developed to represent the transfer function of the OLE channel and is evaluated using computer simulations. The simulations of the OLE system used are based on orthogonal frequency division multiplexing as the chosen modulation scheme. Within the train, for the provision of broadband services, developing a reliable communication system which is a combination of power line communication and optical wireless communication services using visible light communication (VLC) is considered. Mathematical methods were developed for these networks to assess the overall capacities and outage probabilities of the hybrid systems. Derivation of such analytical expressions offered opportunities to investigate the impact of several system parameters on the performance of the system. To assess the possibility of improving the performance of the proposed integrated systems, their performance in the presence of different relaying protocols has been comprehensively analyzed in terms of capacity and outage probability. This thesis studied the outage probability and energy per bit consumption performance of different relaying protocols over the VLC channel. Accurate analytical expressions for the overall outage probability and energyper-bit consumption of the proposed system configurations, including the single-hop and multi-hop approaches were derived. It was found that the transfer function of the OLE channel can be represented by the two-port network model. It was also revealed that transmission over OLE is negatively affected by the speed of the train, frequency, and length of the OLE link. In train, relay-based communication systems can provide reliable connectivity to the end-user. However, choosing an optimal system configuration can enhance system performance. It was also shown that increasing relay numbers on the network contributes to the total power consumption of the system

Secure Routing and Medium Access Protocols inWireless Multi-hop Networks

While the rapid proliferation of mobile devices along with the tremendous growth of various applications using wireless multi-hop networks have significantly facilitate our human life, securing and ensuring high quality services of these networks are still a primary concern. In particular, anomalous protocol operation in wireless multi-hop networks has recently received considerable attention in the research community. These relevant security issues are fundamentally different from those of wireline networks due to the special characteristics of wireless multi-hop networks, such as the limited energy resources and the lack of centralized control. These issues are extremely hard to cope with due to the absence of trust relationships between the nodes. To enhance security in wireless multi-hop networks, this dissertation addresses both MAC and routing layers misbehaviors issues, with main focuses on thwarting black hole attack in proactive routing protocols like OLSR, and greedy behavior in IEEE 802.11 MAC protocol. Our contributions are briefly summarized as follows. As for black hole attack, we analyze two types of attack scenarios: one is launched at routing layer, and the other is cross layer. We then provide comprehensive analysis on the consequences of this attack and propose effective countermeasures. As for MAC layer misbehavior, we particularly study the adaptive greedy behavior in the context of Wireless Mesh Networks (WMNs) and propose FLSAC (Fuzzy Logic based scheme to Struggle against Adaptive Cheaters) to cope with it. A new characterization of the greedy behavior in Mobile Ad Hoc Networks (MANETs) is also introduced. Finally, we design a new backoff scheme to quickly detect the greedy nodes that do not comply with IEEE 802.11 MAC protocol, together with a reaction scheme that encourages the greedy nodes to become honest rather than punishing them

Radio Communications

In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modified our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the field of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks

Mobile Ad-Hoc Networks

Being infrastructure-less and without central administration control, wireless ad-hoc networking is playing a more and more important role in extending the coverage of traditional wireless infrastructure (cellular networks, wireless LAN, etc). This book includes state-of-the-art techniques and solutions for wireless ad-hoc networks. It focuses on the following topics in ad-hoc networks: quality-of-service and video communication, routing protocol and cross-layer design. A few interesting problems about security and delay-tolerant networks are also discussed. This book is targeted to provide network engineers and researchers with design guidelines for large scale wireless ad hoc networks

Interference Mitigation in Multi-Hop Wireless Networks with Advanced Physical-Layer Techniques

In my dissertation, we focus on the wireless network coexistence problem with advanced physical-layer techniques. For the first part, we study the problem of Wireless Body Area Networks (WBAN)s coexisting with cross-technology interference (CTI). WBANs face the RF cross-technology interference (CTI) from non-protocol-compliant wireless devices. Werst experimentally characterize the adverse effect on BAN caused by the CTI sources. Then we formulate a joint routing and power control (JRPC) problem, which aims at minimizing energy consumption while satisfying node reachability and delay constraints. We reformulate our problem into a mixed integer linear programing problem (MILP) and then derive the optimal results. A practical JRPC protocol is then proposed. For the second part, we study the coexistence of heterogeneous multi-hop networks with wireless MIMO. We propose a new paradigm, called cooperative interference mitigation (CIM), which makes it possible for disparate networks to cooperatively mitigate the interference to/from each other to enhance everyone\u27s performance. We establish two tractable models to characterize the CIM behaviors of both networks by using full IC (FIC) and receiver-side IC (RIC) only. We propose two bi-criteria optimization problems aiming at maximizing both networks\u27 throughput, while cooperatively canceling the interference between them based on our two models. In the third and fourth parts, we study the coexistence problem with MIMO from a different point of view: the incentive of cooperation. We propose a novel two-round game framework, based on which we derive two networks\u27 equilibrium strategies and the corresponding closed-form utilities. We then extend our game-theoretical analysis to a general multi-hop case, specifically the coexistence problem between primary network and multi-hop secondary network in the cognitive radio networks domain. In the final part, we study the benefits brought by reconfigurable antennas (RA). We systematically exploit the pattern diversity and fast reconfigurability of RAs to enhance the throughput of MWNs. Werst propose a novel link-layer model that captures the dynamic relations between antenna pattern, link coverage and interference. Based on our model, a throughput optimization framework is proposed by jointly considering pattern selection and link scheduling, which is formulated as a mixed integer non-linear programming problem

Communication between nodes for autonomic and distributed management

Doutoramento conjunto MAPi em InformáticaOver the last decade, the most widespread approaches for traditional management were based on the Simple Network Management Protocol (SNMP) or Common Management Information Protocol (CMIP). However, they both have several problems in terms of scalability, due to their centralization characteristics. Although the distributed management approaches exhibit better performance in terms of scalability, they still underperform regarding communication costs, autonomy, extensibility, exibility, robustness, and cooperation between network nodes. The cooperation between network nodes normally requires excessive overheads for synchronization and dissemination of management information in the network. For emerging dynamic and large-scale networking environments, as envisioned in Next Generation Networks (NGNs), exponential growth in the number of network devices and mobile communications and application demands is expected. Thus, a high degree of management automation is an important requirement, along with new mechanisms that promote it optimally and e ciently, taking into account the need for high cooperation between the nodes. Current approaches for self and autonomic management allow the network administrator to manage large areas, performing fast reaction and e ciently facing unexpected problems. The management functionalities should be delegated to a self-organized plane operating within the network, that decrease the network complexity and the control information ow, as opposed to centralized or external servers. This Thesis aims to propose and develop a communication framework for distributed network management which integrates a set of mechanisms for initial communication, exchange of management information, network (re) organization and data dissemination, attempting to meet the autonomic and distributed management requirements posed by NGNs. The mechanisms are lightweight and portable, and they can operate in di erent hardware architectures and include all the requirements to maintain the basis for an e cient communication between nodes in order to ensure autonomic network management. Moreover, those mechanisms were explored in diverse network conditions and events, such as device and link errors, di erent tra c/network loads and requirements. The results obtained through simulation and real experimentation show that the proposed mechanisms provide a lower convergence time, smaller overhead impact in the network, faster dissemination of management information, increase stability and quality of the nodes associations, and enable the support for e cient data information delivery in comparison to the base mechanisms analyzed. Finally, all mechanisms for communication between nodes proposed in this Thesis, that support and distribute the management information and network control functionalities, were devised and developed to operate in completely decentralized scenarios.Durante a última década, protocolos como Simple Network Management Protocol (SNMP) ou Common Management Information Protocol (CMIP) foram as abordagens mais comuns para a gestão tradicional de redes. Essas abordagens têm vários problemas em termos de escalabilidade, devido às suas características de centralização. Apresentando um melhor desempenho em termos de escalabilidade, as abordagens de gestão distribuída, por sua vez, são vantajosas nesse sentido, mas também apresentam uma série de desvantagens acerca do custo elevado de comunicação, autonomia, extensibilidade, exibilidade, robustez e cooperação entre os nós da rede. A cooperação entre os nós presentes na rede é normalmente a principal causa de sobrecarga na rede, uma vez que necessita de colectar, sincronizar e disseminar as informações de gestão para todos os nós nela presentes. Em ambientes dinâmicos, como é o caso das redes atuais e futuras, espera-se um crescimento exponencial no número de dispositivos, associado a um grau elevado de mobilidade dos mesmos na rede. Assim, o grau elevado de funções de automatiza ção da gestão da rede é uma exigência primordial, bem como o desenvolvimento de novos mecanismos e técnicas que permitam essa comunicação de forma optimizada e e ciente. Tendo em conta a necessidade de elevada cooperação entre os elementos da rede, as abordagens atuais para a gestão autonómica permitem que o administrador possa gerir grandes áreas de forma rápida e e ciente frente a problemas inesperados, visando diminuir a complexidade da rede e o uxo de informações de controlo nela gerados. Nas gestões autonómicas a delegação de operações da rede é suportada por um plano auto-organizado e não dependente de servidores centralizados ou externos. Com base nos tipos de gestão e desa os acima apresentados, esta Tese tem como principal objetivo propor e desenvolver um conjunto de mecanismos necessários para a criação de uma infra-estrutura de comunicação entre nós, na tentativa de satisfazer as exigências da gestão auton ómica e distribuída apresentadas pelas redes de futura geração. Nesse sentido, mecanismos especí cos incluindo inicialização e descoberta dos elementos da rede, troca de informação de gestão, (re) organização da rede e disseminação de dados foram elaborados e explorados em diversas condições e eventos, tais como: falhas de ligação, diferentes cargas de tráfego e exigências de rede. Para além disso, os mecanismos desenvolvidos são leves e portáveis, ou seja, podem operar em diferentes arquitecturas de hardware e contemplam todos os requisitos necessários para manter a base de comunicação e ciente entre os elementos da rede. Os resultados obtidos através de simulações e experiências reais comprovam que os mecanismos propostos apresentam um tempo de convergência menor para descoberta e troca de informação, um menor impacto na sobrecarga da rede, disseminação mais rápida da informação de gestão, aumento da estabilidade e a qualidade das ligações entre os nós e entrega e ciente de informações de dados em comparação com os mecanismos base analisados. Finalmente, todos os mecanismos desenvolvidos que fazem parte da infrastrutura de comunicação proposta foram concebidos e desenvolvidos para operar em cenários completamente descentralizados

Exploring Relay Cooperation for Secure and Reliable Transmission in Two-HopWireless Networks

This work considers the problem of secure and reliable information transmission via relay cooperation in two-hop relay wireless networks without the information of both eavesdropper channels and locations. While previous work on this problem mainly studied infinite networks and their asymptotic behavior and scaling law results, this papers focuses on a more practical network with finite number of system nodes and explores the corresponding exact result on the number of eavesdroppers one network can tolerate to ensure desired secrecy and reliability. We first study the scenario where path-loss is equal between all pairs of nodes and consider two transmission protocols there, one adopts an optimal but complex relay selection process with less load balance capacity while the other adopts a random but simple relay selection process with good load balance capacity. Theoretical analysis and numerical results are then provided to determine the maximum number of eavesdroppers one network can tolerate to ensure a desired performance in terms of the secrecy outage probability and transmission outage probability. We further extend our study to the more general scenario where path-loss between each pair of nodes also depends on the distance between them, for which a new transmission protocol with both preferable relay selection and good load balance as well as the corresponding theoretical analysis and numerical results are presented