23 research outputs found

    Learning and Reasoning Strategies for User Association in Ultra-dense Small Cell Vehicular Networks

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    Recent vehicular ad hoc networks research has been focusing on providing intelligent transportation services by employing information and communication technologies on road transport. It has been understood that advanced demands such as reliable connectivity, high user throughput, and ultra-low latency required by these services cannot be met using traditional communication technologies. Consequently, this thesis reports on the application of artificial intelligence to user association as a technology enabler in ultra-dense small cell vehicular networks. In particular, the work focuses on mitigating mobility-related concerns and networking issues at different mobility levels by employing diverse heuristic as well as reinforcement learning (RL) methods. Firstly, driven by rapid fluctuations in the network topology and the radio environment, a conventional, three-step sequence user association policy is designed to highlight and explore the impact of vehicle speed and different performance indicators on network quality of service (QoS) and user experience. Secondly, inspired by control-theoretic models and dynamic programming, a real-time controlled feedback user association approach is proposed. The algorithm adapts to the changing vehicular environment by employing derived network performance information as a heuristic, resulting in improved network performance. Thirdly, a sequence of novel RL based user association algorithms are developed that employ variable learning rate, variable rewards function and adaptation of the control feedback framework to improve the initial and steady-state learning performance. Furthermore, to accelerate the learning process and enhance the adaptability and robustness of the developed RL algorithms, heuristically accelerated RL and case-based transfer learning methods are employed. A comprehensive, two-tier, event-based, system level simulator which is an integration of a dynamic vehicular network, a highway, and an ultra-dense small cell network is developed. The model has enabled the analysis of user mobility effects on the network performance across different mobility levels as well as served as a firm foundation for the evaluation of the empirical properties of the investigated approaches

    Connected vehicles for internet access: deployment and spectrum policies

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    Internet traffic from mobile users has been growing sharply. To meet the needs of thoseusers, it is important to expand capacity of networks that provide Internet access in cost effectiveways. This capacity has traditionally been provided by cellular networks. However,expanding the capacity of those networks alone may not be the most cost-effective way to meetthe present and future growth of mobile Internet under some circumstances. In this dissertation,we show that networks of connected vehicles can be an important way to complement thecapacity of cellular networks to provide mobile Internet access under several scenarios.Connected vehicles may soon be widely deployed, forming mesh networks of short-rangeconnections among vehicles and between vehicles and roadside infrastructure. Theseconnections are collectively referred to as vehicle-to-everything, or V2X. Deployment ofconnected vehicles and infrastructure is primarily intended to enhance road safety, and the U.S.Department of Transportation has recently proposed a mandate of V2X devices in vehiclesusing Dedicated Short Range Communications (DSRC) technology. Other applications are alsoenvisioned that include Internet access in vehicles connecting to roadside infrastructure servingas gateways to the Internet.In this work, we find that V2X-based networks are more cost-effective than cellular toprovide Internet access, in scenarios which DSRC devices are mandated in vehicles to enhanceroad safety. This is true initially for densely populated urban areas, but over time V2X-basednetworks would be cost-effective in less populated areas as well, as long as Internet traffic orpenetration of V2X devices grow as expected.Local and state governments are expected to deploy roadside infrastructure for safetyapplications. If that infrastructure is shared with Internet Service Providers for a fee, then V2XABSTRACT based networks are cost-effective in locations with even lower population densities than thelocations where it is cost-effective to deploy infrastructure for Internet access only. Moreover,the sharing fee could help governments save in infrastructure costs. We find the pricingstrategies that maximize either cost-effectiveness or government savings. We estimate thatgovernments could save about one-fifth of the total cost to deploy safety infrastructurenationwide in the U.S., if fees are set to maximize government savings. Although we find thatthese prices may differ from the pricing strategy that maximizes cost-effectiveness, maximizinggovernment savings results in near-optimal cost-effectiveness.The U.S. Federal Communications Commission has allocated 75 MHz of spectrum to beused exclusively by DSRC devices, and it has been hotly debated whether all or part of thatbandwidth should be shared with unlicensed devices. We find that it is highly efficient to shareany spectrum allocated to V2X communications beyond the portion of that spectrum that isneeded for safety-critical DSRC messages. V2X and unlicensed devices require up to 50% lessbandwidth on shared spectrum to achieve given throughputs, compared to V2X and unlicenseddevices using separate bands. We conclude that the spectrum available for V2X should bemaintained or increased, as long as much of that spectrum is shared with non-V2X devices.Conclusions are derived from an engineering-economic approach, in which part of theassumptions are based on data from a citywide deployment of connected vehicles in Portugal.The data is used in a detailed and realistic packet-level simulation model of V2X-basednetworks used to provide Internet access with DSRC technology. In some scenarios, thesimulation also includes unlicensed devices using Wi-Fi technology. The results of the networksimulation are then fed into engineering-economic models to compare costs of V2X-basednetworks with costs of macrocellular networks to carry given amounts of Internet traffic, and toestimate other measures such as government revenues and spectrum usage. Those measureshelp inform decisions about where and when to deploy V2X-based networks, decisions about whether and how to promote public-private partnerships to deploy V2X infrastructure, anddecisions about sharing spectrum used for V2X communications with non-V2X devices. <br

    Terminal cooperation in next generation wireless networks: aerial and regional access networks

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    Throughout the years, progress of humankind has depended on the power of communication and over the decades, the ways of communication has witnessed mammoth changes. Specifically wireless communication in the last decade has completely revolutionized the way we communicate with each other. Smartphones have become an ubiquitous part of our life. With most operators throughout the world deploying fourth generation wireless communication systems, peculiar use cases and scenarios are being envisioned such as public safety networks, aerial networks, etc. to be addressed by the next generation wireless systems. Moreover, as urban areas are becoming saturated commercial network operators are looking for business cases to move towards the untapped regional areas. However, to deploy networks in regional areas economically, novel technologies and architectures need to be developed and investigated. In this thesis, we study the novel concept of terminal cooperation in the context of next generation wireless communication systems especially looking into aerial and regional access networks. In the first part of the thesis, we investigate the physical radio channel for device-to-device (D2D) communication which would help in enabling terminal cooperation in wireless networks. Specifically, we propose propagation model for D2D in rural areas using 922 MHz and 2466 MHz, a channel model for vehicular communications using 5.8 GHz and a propagation model for D2D using millimetre wave frequencies. In the second part of the thesis, we evaluate the coverage performance of aerial access networks using different technologies and develop algorithms to enhance the coverage using terminal cooperation in regional access networks. Specifically, we evaluate the performance of two different technologies, LTE and WiFi, in aerial access networks. We propose game-theoretic algorithms to enable terminal cooperation to enhance coverage in regional access networks and perform system level simulation to evaluate the proposed algorithms. In the last part of this thesis, we analyse and develop techniques to enhance energy efficiency in aerial access networks using terminal cooperation. Specifically, we propose a clustering algorithm called EECAN which improves the energy efficiency of the terrestrial nodes accessing the aerial base-station, a clustering algorithm based on Matern Hardcore Point Process which allows us to optimize cluster head spacing analytically and we further enhance this algorithm by including impairments introduced by the wireless channel. Throughout this thesis, we verify and validate our analytic results, algorithms and techniques with Monte-Carlo simulations of the considered scenarios. Most of the work presented in this thesis was published in-part or as a whole in conferences, journals, book-chapters, project reports or otherwise undergoing a review process. These publications and reports are highlighted in the course of the thesis. Lastly, we invite the reader to enjoy exploring this thesis and we hope that it will add more understanding to this promising new technology of terminal cooperation in aerial and regional access networks

    Modelling and Real Deployment of C-ITS by Integrating Ground Vehicles and Unmanned Aerial Vehicles

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    [ES] Para proporcionar un entorno de tr谩fico vial m谩s seguro y eficiente, los sistemas ITS o Sistemas Inteligentes de Transporte representan como una soluci贸n dotada de avances tecnol贸gicos de vanguardia. La integraci贸n de elementos de transporte como autom贸viles junto con elementos de infraestructura como RoadSide Units (RSUs) ubicados a lo largo de la v铆a de comunicaci贸n permiten ofrecer un entorno de red conectado con m煤ltiples servicios, incluida conectividad a Internet. Esta integraci贸n se conoce con el t茅rmino C-ITS o Sistemas Inteligentes de Transporte Cooperativos. La conexi贸n de autom贸viles con dispositivos de infraestructura permite crear redes vehiculares conectadas (V2X) veh铆culo a dispositivos, que ofrecen la posibilidad de nuevos despliegues en aplicaciones C-ITS como las relacionadas con la seguridad. Hoy en d铆a, con el uso masivo de tel茅fonos inteligentes y debido a su flexibilidad y movilidad, existen varios esfuerzos para integrarlos con los autom贸viles. De hecho, con el soporte adecuado de unidad a bordo (OBU), los tel茅fonos inteligentes se pueden integrar perfectamente con las redes vehiculares, permitiendo a los conductores usar sus tel茅fonos inteligentes como dispositivos de bordo a que participan en los servicios C-ITS, con el objeto de mejorar la seguridad al volante entre otros. T贸pico este, que hoy d铆a representa un tema relevante de investigaci贸n. Un problema a solucionar surge cuando las comunicaciones vehiculares sufren inferencias y bloqueos de la se帽al debidos al escenario. De hecho, el impacto de la vegetaci贸n y los edificios, ya sea en 谩reas urbanas y rurales, puede afectar a la calidad de la se帽al. Algunas estrategias para mejorar la comunicaci贸n vehicular en este tipo de entorno consiste en desplegar UAVs o veh铆culo a茅reo no tripulado (drones), los cuales act煤an como enlaces de comunicaci贸n entre veh铆culos. De hecho, UAV ofrece importantes ventajas de implementaci贸n, ya que tienen una gran flexibilidad en t茅rminos de movilidad, adem谩s de un rango de comunicaciones mejorado. Para evaluar la calidad de las comunicaciones, debe realizarse un conjunto de mediciones. Sin embargo, debido al costo de las implementaciones reales de UAV y autom贸viles, los experimentos reales podr铆an no ser factibles para actividades de investigaci贸n con recursos limitados. Por lo tanto, los experimentos de simulaci贸n se convierten en la opci贸n preferida para evaluar las comunicaciones entre UAV y veh铆culos terrestres. Lograr modelos de propagaci贸n de se帽al correctos y representativos que puedan importarse a los entornos de simulaci贸n se vuelve crucial para obtener un mayor grado de realismo, especialmente para simulaciones que involucran el movimiento de UAVs en cualquier lugar del espacio 3D. En particular, la informaci贸n de elevaci贸n del terreno debe tenerse en cuenta al intentar caracterizar los efectos de propagaci贸n de la se帽al. En esta tesis doctoral, proponemos nuevos enfoques tanto te贸ricos como emp铆ricos para estudiar la integraci贸n de redes vehiculares que combinan autom贸viles y UAVs, as铆 mismo el impacto del entorno en la calidad de las comunicaciones. Esta tesis presenta una aplicaci贸n, una metodolog铆a de medici贸n en escenarios reales y un nuevo modelo de simulaci贸n, los cuales contribuyen a modelar, desarrollar e implementar servicios C-ITS. M谩s espec铆ficamente, proponemos un modelo de simulaci贸n que tiene en cuenta las caracter铆sticas del terreno en 3D, para lograr resultados confiables de comunicaci贸n entre UAV y veh铆culos terrestres.[CA] Per a proporcionar un entorn de tr脿nsit viari m茅s segur i eficient, els sistemes ITS o Sistemes Intel路ligents de Transport representen una soluci贸 dotada d'avan莽os tecnol貌gics d'avantguarda. La integraci贸 d'elements de transport com auto m贸vils juntament amb elements d'infraestructura com Road Side Units (RSUs) situats al llarg de lav via de comunicaci贸 permeten oferir un entorn de xarxa connectat amb multiples serveis, inclusa connectivitat a Internet. Aquesta integraci贸 es connex amb el terme C-ITS o Sistemes Intel路ligents de Transport Cooperatius , com ara els autom貌bils, amb elements d'infraestructura, com ara les road side units (RSU) o pals situats al llarg de la carretera, per a aconseguir un entorn de xarxa que oferisca nous serveis a m茅s de connectivitat a Internet. Aquesta integraci贸 s'expressa amb el terme C-ITS, o sistemes intel路ligents de transport cooperatius. La connexi贸 d'autom貌bils amb dispositius d'infraestructura permet crear xarxes vehiculars connectades (V2X) vehicle a dispositiu, que ofreixen la possibilitat de nous desplegaments en aplicacions C-ITS, com ara les relacionades amb la seguretat. Avui dia, amb l'煤s massiu dels tel猫fons intel路ligents, i a causa de la flexibilitat i mobilitat que presenten, es fan esfor莽os per integrar-los amb els autom貌bils. De fet, amb el suport adequat d'unitat a bord (OBU), els tel猫fons intel路ligents es poden integrar perfectament amb les xarxes vehiculars, permetent als conductors usar els seus tel猫fons intel路ligents com a dispositius per a participar en els serveis de C-ITS, a fi de millorar la seguretat al volant entre altres. T貌pic est, que hui dia representa un tema rellevant d'investigaci贸. Un problema a solucionar sorgeix quan les comunicacions vehiculars ateixen infer猫ncies i bloquejos del senyal deguts a l'escenari. De fet, l'impacte de la vegetaci贸 i els edificis, tant en 脿rees urbanes com rurals, pot afectar la qualitat del senyal. Algunes estrat猫gies de millorar la comunicaci贸 vehicular en aquest tipus d'entorn consisteix a desplegar UAVs o vehicles aeris no tripulats (drones), els quals actuen com a enlla莽os de comunicaci贸 entre vehicles. De fet, l'煤s d'UAVs ofereix importants avantatges d'implementaci贸, ja que tenen una gran flexibilitat en termes de mobilitat, a m茅s d'un rang de comunicacions millorat. Per a avaluar la qualitat de les comunicacions, s'han de realitzar mesures en escenaris reals. No obstant aix貌, a causa del cost de les implementacions i desplegaments reals d'UAV i el seu 煤s combinat amb vehicles, aquests experiments reals podrien no ser factibles per a activitats d'investigaci贸 amb recursos limitats. Per tant, la metodologia basada en simulaci贸 es converteixen en l'opci贸 preferida entre els investigadors per a avaluar les comunicacions entre UAV i vehicles terrestres. Aconseguir models de propagaci贸 de senyal correctes i representatius que puguen importar-se als entorns de simulaci贸 resulta crucial per a obtenir un major grau de realisme, especialment per a simulacions que involucren el moviment d'UAV en qualsevol lloc de l'espai 3D. En particular, cal tenir en compte la informaci贸 d'elevaci贸 del terreny per a intentar caracteritzar els efectes de propagaci贸 del senyal. En aquesta tesi doctoral proposem enfocaments tant te貌rics com emp铆rics per a estudiar la integraci贸 de xarxes vehiculars que combinen autom貌bils i UAV, aix铆 com l'impacte de l'entorn en la qualitat de les comunicacions. Aquesta tesi presenta una aplicaci贸, una metodolog铆a de mesurament en escenaris reals i un nou model de simulaci贸, els quals contribueixen a modelar, desenvolupar i implementar serveis C-ITS. M茅s espec铆ficament, proposem un model de simulaci贸 que t茅 en compte les caracter铆stiques del terreny en 3D, per a aconseguir resultats fiables de comunicaci贸 entre UAV i vehicles terrestres.[EN] To provide a safer road traffic environment and make it more convenient, Intelligent Transport Systems (ITSs) are proposed as a solution endowed with cutting-edge technological advances. The integration of transportation elements like cars together with infrastructure elements like Road Side Units to achieve a networking environment offers new services in addition to Internet connectivity. This integration comes under the term Cooperative Intelligent Transport System (C-ITS). Connecting cars with surrounding devices forming vehicular networks in Vehicle-to-Everything (V2X) open new deployments in C-ITS applications like safety-related ones. With the massive use of smartphones nowadays, and due to their flexibility and mobility, several efforts exist to integrate them with cars. In fact, with the right support from the vehicle's On-Board Unit (OBU), smartphones can be seamlessly integrated with vehicular networks. Hence, drivers can use their smartphones as a device to participate in C-ITS services for safety purposes, among others, which is a quite interesting research topic. A significant problem arises when vehicular communications face signal obstructions caused by the environment. In fact, the impact of vegetation and buildings, whether in urban and rural areas, can result in a lower signal quality. One way to enhance vehicular communication networks is to deploy Unmanned Aerial Vehicles (UAVs) to act as relays for communication between cars, or ground vehicles. In fact, UAVs offer important deployment advantages, as they offer great flexibility in terms of mobility, in addition to an enhanced communications range. To assess the quality of the communications, a set of measurements must take place. However, due to the cost of real deployments of UAVs and cars, real experiments might not be feasible for research activities with limited resources. Hence, simulation experiments become the preferred option to assess UAV-to- car communications. Achieving correct and representative signal propagation models that can be imported to the simulation environments becomes crucial to obtain a higher degree of realism, especially for simulations involving UAVs moving anywhere throughout the 3D space. In particular, terrain elevation information must be taken into account when attempting to characterize signal propagation effects. In this research work, we propose both theoretical and empirical approaches to study the integration of vehicular networks combining cars and UAVs, and we study the impact of the surrounding environment on the communications quality. An application, a measurement framework, and a simulation model are presented in this thesis in an effort to model, develop, and deploy C-ITS services. More specifically, we propose a simulation model that takes into account 3D terrain features to achieve reliable UAV-to-car communication results.I want to thank the Spanish government through the Ministry of Economy and Competitiveness (MINECO) and the European Union Commission through the European Social Fund (ESF) for co-financing and granting me the fellowship to fund my studies in Spain and my research stay in Russia. In addition, I would to thank the National Institute of Informatics for granting me the internship fund and the Japanese government through the Japan Society for the Promotion of Science (JSPS) for supporting my research work in Japan.Hadiwardoyo, SA. (2019). Modelling and Real Deployment of C-ITS by Integrating Ground Vehicles and Unmanned Aerial Vehicles [Tesis doctoral no publicada]. Universitat Polit猫cnica de Val猫ncia. https://doi.org/10.4995/Thesis/10251/118796TESI

    Wireless communication, sensing, and REM: A security perspective

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    The diverse requirements of next-generation communication systems necessitate awareness, flexibility, and intelligence as essential building blocks of future wireless networks. The awareness can be obtained from the radio signals in the environment using wireless sensing and radio environment mapping (REM) methods. This is, however, accompanied by threats such as eavesdropping, manipulation, and disruption posed by malicious attackers. To this end, this work analyzes the wireless sensing and radio environment awareness mechanisms, highlighting their vulnerabilities and provides solutions for mitigating them. As an example, the different threats to REM and its consequences in a vehicular communication scenario are described. Furthermore, the use of REM for securing communications is discussed and future directions regarding sensing/REM security are highlighted

    Performance evaluation of future wireless networks: node cooperation and aerial networks

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    Perhaps future historians will only refer to this era as the \emph{information age}, and will recognize it as a paramount milestone in mankind progress. One of the main pillars of this age is the ability to transmit and communicate information effectively and reliably, where wireless radio technology became one of the most vital enablers for such communication. A growth in radio communication demand is notably accelerating in a never-resting pace, pausing a great challenge not only on service providers but also on researches and innovators to explore out-of-the-box technologies. These challenges are mainly related to providing faster data communication over seamless, reliable and cost efficient wireless network, given the limited availability of physical radio resources, and taking into consideration the environmental impact caused by the increasing energy consumption. Traditional wireless communication is usually deployed in a cellular manner, where fixed base stations coordinate radio resources and play the role of an intermediate data handler. The concept of cellular networks and hotspots is widely adopted as the current stable scheme of wireless communication. However in many situations this fixed infrastructure could be impaired with severe damages caused by natural disasters, or could suffer congestions and traffic blockage. In addition to the fact that in the current networks any mobile-to-mobile data sessions should pass through the serving base station that might cause unnecessary energy consumption. In order to enhance the performance and reliability of future wireless networks and to reduce its environmental footprint, we explore two complementary concepts: the first is node cooperation and the second is aerial networks. With the ability of wireless nodes to cooperate lays two main possible opportunities; one is the ability of the direct delivery of information between the communicating nodes without relaying traffic through the serving base station, thus reducing energy consumption and alleviating traffic congestion. A second opportunity would be that one of the nodes helps a farther one by relaying its traffic towards the base station, thus extending network coverage and reliability. Both schemes can introduce significant energy saving and can enhance the overall availability of wireless networks in case of natural disasters. In addition to node cooperation, a complementary technology to explore is the \emph{aerial networks} where base stations are airborne on aerial platforms such as airships, UAVs or blimps. Aerial networks can provide a rapidly deployable coverage for remote areas or regions afflicted by natural disasters or even to patch surge traffic demand in public events. Where node cooperation can be implemented to complement both regular terrestrial coverage and to complement aerial networks. In this research, we explore these two complementary technologies, from both an experimental approach and from an analytic approach. From the experimental perspective we shed the light on the radio channel properties that is hosting terrestrial node cooperation and air-to-ground communication, namely we utilize both simulation results and practical measurements to formulate radio propagation models for device-to-device communication and for air-to-ground links. Furthermore we investigate radio spectrum availability for node cooperation in different urban environment, by conductive extensive mobile measurement survey. Within the experimental approach, we also investigate a novel concept of temporary cognitive femtocell network as an applied solution for public safety communication networks during the aftermath of a natural disaster. While from the analytical perspective, we utilize mathematical tools from stochastic geometry to formulate novel analytical methodologies, explaining some of the most important theoretical boundaries of the achievable enhancements in network performance promised by node cooperation. We start by determining the estimated coverage and rate received by mobile users from convectional cellular networks and from aerial platforms. After that we optimize this coverage and rate ensuring that relay nodes and users can fully exploit their coverage efficiently. We continue by analytically quantifying the cellular network performance during massive infrastructure failure, where some nodes play the role of low-power relays forming multi-hop communication links to assist farther nodes outside the reach of the healthy network coverage. In addition, we lay a mathematical framework for estimating the energy saving of a mediating relay assisting a pair of wireless devices, where we derive closed-form expressions for describing the geometrical zone where relaying is energy efficient. Furthermore, we introduce a novel analytic approach in analyzing the energy consumption of aerial-backhauled wireless nodes on ground fields through the assistance of an aerial base station, the novel mathematical framework is based on Mat\&#039;{e}rn hard-core point process. Then we shed the light on the points interacting of these point processes quantifying their main properties. Throughout this thesis we relay on verifying the analytic results and formulas against computer simulations using Monte-Carlo analysis. We also present practical numerical examples to reflect the usefulness of the presented methodologies and results in real life scenarios. Most of the work presented in this dissertation was published in-part or as a whole in highly ranked peer-reviewed journals, conference proceedings, book chapters, or otherwise currently undergoing a review process. These publications are highlighted and identified in the course of this thesis. Finally, we wish the reader to enjoy exploring the journey of this thesis, and hope it will add more understanding to the promising new technologies of aerial networks and node cooperation
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