cISP: A Speed-of-Light Internet Service Provider

Low latency is a requirement for a variety of interactive network applications. The Internet, however, is not optimized for latency. We thus explore the design of cost-effective wide-area networks that move data over paths very close to great-circle paths, at speeds very close to the speed of light in vacuum. Our cISP design augments the Internet's fiber with free-space wireless connectivity. cISP addresses the fundamental challenge of simultaneously providing low latency and scalable bandwidth, while accounting for numerous practical factors ranging from transmission tower availability to packet queuing. We show that instantiations of cISP across the contiguous United States and Europe would achieve mean latencies within 5% of that achievable using great-circle paths at the speed of light, over medium and long distances. Further, we estimate that the economic value from such networks would substantially exceed their expense

A Survey on the Contributions of Software-Defined Networking to Traffic Engineering

Since the appearance of OpenFlow back in 2008, software-defined networking (SDN) has gained momentum. Although there are some discrepancies between the standards developing organizations working with SDN about what SDN is and how it is defined, they all outline traffic engineering (TE) as a key application. One of the most common objectives of TE is the congestion minimization, where techniques such as traffic splitting among multiple paths or advanced reservation systems are used. In such a scenario, this manuscript surveys the role of a comprehensive list of SDN protocols in TE solutions, in order to assess how these protocols can benefit TE. The SDN protocols have been categorized using the SDN architecture proposed by the open networking foundation, which differentiates among data-controller plane interfaces, application-controller plane interfaces, and management interfaces, in order to state how the interface type in which they operate influences TE. In addition, the impact of the SDN protocols on TE has been evaluated by comparing them with the path computation element (PCE)-based architecture. The PCE-based architecture has been selected to measure the impact of SDN on TE because it is the most novel TE architecture until the date, and because it already defines a set of metrics to measure the performance of TE solutions. We conclude that using the three types of interfaces simultaneously will result in more powerful and enhanced TE solutions, since they benefit TE in complementary ways.European Commission through the Horizon 2020 Research and Innovation Programme (GN4) under Grant 691567 Spanish Ministry of Economy and Competitiveness under the Secure Deployment of Services Over SDN and NFV-based Networks Project S&NSEC under Grant TEC2013-47960-C4-3-

Measuring And Improving Internet Video Quality Of Experience

Streaming multimedia content over the IP-network is poised to be the dominant Internet traffic for the coming decade, predicted to account for more than 91% of all consumer traffic in the coming years. Streaming multimedia content ranges from Internet television (IPTV), video on demand (VoD), peer-to-peer streaming, and 3D television over IP to name a few. Widespread acceptance, growth, and subscriber retention are contingent upon network providers assuring superior Quality of Experience (QoE) on top of todays Internet. This work presents the first empirical understanding of Internet’s video-QoE capabilities, and tools and protocols to efficiently infer and improve them. To infer video-QoE at arbitrary nodes in the Internet, we design and implement MintMOS: a lightweight, real-time, noreference framework for capturing perceptual quality. We demonstrate that MintMOS’s projections closely match with subjective surveys in accessing perceptual quality. We use MintMOS to characterize Internet video-QoE both at the link level and end-to-end path level. As an input to our study, we use extensive measurements from a large number of Internet paths obtained from various measurement overlays deployed using PlanetLab. Link level degradations of intra– and inter–ISP Internet links are studied to create an empirical understanding of their shortcomings and ways to overcome them. Our studies show that intra–ISP links are often poorly engineered compared to peering links, and that iii degradations are induced due to transient network load imbalance within an ISP. Initial results also indicate that overlay networks could be a promising way to avoid such ISPs in times of degradations. A large number of end-to-end Internet paths are probed and we measure delay, jitter, and loss rates. The measurement data is analyzed offline to identify ways to enable a source to select alternate paths in an overlay network to improve video-QoE, without the need for background monitoring or apriori knowledge of path characteristics. We establish that for any unstructured overlay of N nodes, it is sufficient to reroute key frames using a random subset of k nodes in the overlay, where k is bounded by O(lnN). We analyze various properties of such random subsets to derive simple, scalable, and an efficient path selection strategy that results in a k-fold increase in path options for any source-destination pair; options that consistently outperform Internet path selection. Finally, we design a prototype called source initiated frame restoration (SIFR) that employs random subsets to derive alternate paths and demonstrate its effectiveness in improving Internet video-QoE

Contributions to the routing of traffic flows in multi-hop IEEE 802.11 wireless networks

The IEEE 802.11 standard was not initially designed to provide multi-hop capabilities. Therefore, providing a proper traffic performance in Multi-Hop IEEE 802.11 Wireless Networks (MIWNs) becomes a significant challenge. The approach followed in this thesis has been focused on the routing layer in order to obtain applicable solutions not dependent on a specific hardware or driver. Nevertheless, as is the case of most of the research on this field, a cross-layer design has been adopted. Therefore, one of the first tasks of this work was devoted to the study of the phenomena which affect the performance of the flows in MIWNs. Different estimation methodologies and models are presented and analyzed. The first main contribution of this thesis is related to route creation procedures. First, FB-AODV is introduced, which creates routes and forwards packets according to the flows on the contrary to basic AODV which is destination-based. This enhancement permits to balance the load through the network and gives a finer granularity in the control and monitoring of the flows. Results showed that it clearly benefits the performance of the flows. Secondly, a novel routing metric called Weighted Contention and Interference routing Metric (WCIM) is presented. In all analyzed scenarios, WCIM outperformed the other analyzed state-of-the-art routing metrics due to a proper leveraging of the number of hops, the link quality and the suffered contention and interference. The second main contribution of this thesis is focused on route maintenance. Generally, route recovery procedures are devoted to the detection of link breaks due to mobility or fading. However, other phenomena like the arrival of new flows can degrade the performance of active flows. DEMON, which is designed as an enhancement of FB-AODV, allows the preemptive recovery of degraded routes by passively monitoring the performance of active flows. Results showed that DEMON obtains similar or better results than other published solutions in mobile scenarios, while it clearly outperforms the performance of default AODV under congestion Finally, the last chapter of this thesis deals with channel assignment in multi-radio solutions. The main challenge of this research area relies on the circular relationship between channel assignment and routing; channel assignment determines the routes that can be created, while the created routes decide the real channel diversity of the network and the level of interference between the links. Therefore, proposals which join routing and channel assignment are generally complex, centralized and based on traffic patterns, limiting their practical implementation. On the contrary, the mechanisms presented in this thesis are distributed and readily applicable. First, the Interference-based Dynamic Channel Assignment (IDCA) algorithm is introduced. IDCA is a distributed and dynamic channel assignment based on the interference caused by active flows which uses a common channel in order to assure connectivity. In general, IDCA leads to an interesting trade-off between connectivity preservation and channel diversity. Secondly, MR-DEMON is introduced as way of joining channel assignment and route maintenance. As DEMON, MR-DEMON monitors the performance of the active flows traversing the links, but, instead of alerting the source when noticing degradation, it permits reallocating the flows to less interfered channels. Joining route recovery instead of route creation simplifies its application, since traffic patterns are not needed and channel reassignments can be locally decided. The evaluation of MR-DEMON proved that it clearly benefits the performance of IDCA. Also, it improves DEMON functionality by decreasing the number of route recoveries from the source, leading to a lower overhead.El estándar IEEE 802.11 no fue diseñado inicialmente para soportar capacidades multi-salto. Debido a ello, proveer unas prestaciones adecuadas a los flujos de tráfico que atraviesan redes inalámbricas multi-salto IEEE 802.11 supone un reto significativo. La investigación desarrollada en esta tesis se ha centrado en la capa de encaminamiento con el objetivo de obtener soluciones aplicables y no dependientes de un hardware específico. Sin embargo, debido al gran impacto de fenómenos y parámetros relacionados con las capas físicas y de acceso al medio sobre las prestaciones de los tráficos de datos, se han adoptado soluciones de tipo cross-layer. Es por ello que las primeras tareas de la investigación, presentadas en los capítulos iniciales, se dedicaron al estudio y caracterización de estos fenómenos. La primera contribución principal de esta tesis se centra en mecanismos relacionados con la creación de las rutas. Primero, se introduce una mejora del protocolo AODV, que permite crear rutas y encaminar paquetes en base a los flujos de datos, en lugar de en base a los destinos como se da en el caso básico. Esto permite balacear la carga de la red y otorga un mayor control sobre los flujos activos y sus prestaciones, mejorando el rendimiento general de la red. Seguidamente, se presenta una métrica de encaminamiento sensible a la interferencia de la red y la calidad de los enlaces. Los resultados analizados, basados en la simulación de diferentes escenarios, demuestran que mejora significativamente las prestaciones de otras métricas del estado del arte. La segunda contribución está relacionada con el mantenimiento de las rutas activas. Generalmente, los mecanismos de mantenimiento se centran principalmente en la detección de enlaces rotos debido a la movilidad de los nodos o a la propagación inalámbrica. Sin embargo, otros fenómenos como la interferencia y congestión provocada por la llegada de nuevos flujos pueden degradar de forma significativa las prestaciones de los tráficos activos. En base a ello, se diseña un mecanismo de mantenimiento preventivo de rutas, que monitoriza las prestaciones de los flujos activos y permite su reencaminamiento en caso de detectar rutas degradadas. La evaluación de esta solución muestra una mejora significativa sobre el mantenimiento de rutas básico en escenarios congestionados, mientras que en escenarios con nodos móviles obtiene resultados similares o puntualmente mejores que otros mecanismos preventivos diseñados específicamente para casos con movilidad. Finalmente, el último capítulo de la tesis se centra en la asignación de canales en entornos multi-canal y multi-radio con el objetivo de minimizar la interferencia entre flujos activos. El reto principal en este campo es la dependencia circular que se da entre la asignación de canales y la creación de rutas: la asignación de canales determina los enlaces existentes la red y por ello las rutas que se podrán crear, pero son finalmente las rutas y los tráficos activos quienes determinan el nivel real de interferencia que se dará en la red. Es por ello que las soluciones que proponen unificar la asignación de canales y el encaminamiento de tráficos son generalmente complejas, centralizadas y basadas en patrones de tráfico, lo que limita su implementación en entornos reales. En cambio, en nuestro caso adoptamos una solución distribuida y con mayor aplicabilidad. Primero, se define un algoritmo de selección de canales dinámico basado en la interferencia de los flujos activos, que utiliza un canal común en todos los nodos para asegurar la conectividad de la red. A continuación, se introduce un mecanismo que unifica la asignación de canales con el mantenimiento preventivo de las rutas, permitiendo reasignar flujos degradados a otros canales disponibles en lugar de reencaminarlos completamente. Ambas soluciones demuestran ser beneficiosas en este tipo de entornos.Postprint (published version

Resilient communications in smart grids

Tese de mestrado, Segurança Informática, Universidade de Lisboa, Faculdade de Ciências, 2018As redes elétricas, algumas já centenárias, foram concebidas para uma realidade bastante diferente da actual. O facto de terem sido desenhadas para transportar e distribuir a energia de forma unidirecional, torna a infraestrutura rígida, causando problemas em termos de escalabilidade e dificulta a sua evolução. Conhecidas questões ambientais têm levado a que a geração de energia baseada em combustíveis fosseis seja substituída pela geração através de fontes de energia renováveis. Esta situação motivou a criação de incentivos ao investimento nas fontes de energia renováveis, o que levou a que cada vez mais consumidores apostem na microgeração. Estas alterações causaram uma mudança na forma como é feita a produção e distribuição de energia elétrica, com uma aposta crescente na interligação entre as várias fontes ao longo da infraestrutura, tornando a gestão destas redes uma tarefa extremamente complexa. Com o crescimento significativo de consumidores que também podem ser produtores, torna-se essencial uma coordenação cuidada na injeção de energia na rede. Este facto, aliado à crescente utilização de energia elétrica, faz com que a manutenção da estabilidade da rede seja um enorme desafio. As redes inteligentes, ou smart grids, propõem resolver muitos dos problemas que surgiram com esta alteração do paradigma de consumo/produção de energia elétrica. Os componentes da rede passam a comunicar uns com os outros, tornando a rede eléctrica bidirecional, facilitando assim a sua manutenção e gestão. A possibilidade de constante troca de informação entre todos os componentes que constituem a smart grid permite uma reação imediata relativamente às ações dos produtores e consumidores de energia elétrica. No entanto, com esta alteração de paradigma surgiram também muitos desafios. Nomeadamente, a necessidade de comunicação entre os equipamentos existentes nas smart grids leva a que as redes de comunicação tenham de cobrir grandes áreas. Essa complexidade aumenta quando a gestão necessita de ser feita ao nível de cada equipamento e não de forma global. Isto ´e devido ao facto de nas redes de comunicação tradicionais, o plano de controlo e o de dados estarem no mesmo equipamento, o que leva a que o seu controlo seja difícil e propício a erros. Este controlo descentralizado dificulta também a reorganização da rede quando ocorrem faltas pelo facto de não existir um dispositivo que tenha o conhecimento completo da rede. A adaptação rápida a faltas de forma a tornar a comunicação resiliente tem grande importância em redes sensíveis a latência como é o caso da smart grid, pelo que mecanismos eficientes de tolerância a faltas devem ser implementados. As redes definidas por software, ou Software Defined Networks (SDN), surgem como uma potencial solução para estes problemas. Através da separação entre o plano de controlo e o plano de dados, permite a centralização lógica do controlo da rede no controlador. Para tal, é necessário adicionar uma camada de comunicação entre o controlador e os dispositivos de rede, através de um protocolo como o Openflow. Esta separação reduz a complexidade da gestão da rede e a centralização lógica torna possível programar a rede de forma global, de modo a aplicar as políticas pretendidas. Estes fatores tornam a SDN uma soluçãoo interessante para utilizar em smart grids. Esta tese investiga formas de tornar a rede de comunicações empregue numa smart grid resiliente a faltas. Pelas vantagens mencionadas anteriormente, é usada uma solução baseada em SDN, sendo propostos dois módulos essenciais. O primeiro tem como objectivo a monitorização segura da rede, permitindo obter em tempo real métricas como largura de banda, latência e taxa de erro. O segundo módulo trata do roteamento e engenharia de tráfego, utilizando a informação fornecida pelo módulo de monitorização de forma a que os componentes da smart grid comuniquem entre si, garantindo que os requisitos das aplicações são cumpridos. Dada a criticidade da rede elétrica e a importância das comunicações na smart grid, os mecanismos desenvolvidos toleram faltas, quer de tipo malicioso, quer de tipo acidental.The evolution on how electricity is produced and consumed has made the management of power grids an extremely complex task. Today’s centenary power grids were not designed to fit a new reality where consumers can also be producers, or the impressive increase in consumption caused by more sophisticated and powerful appliances. Smart Grids have been prepared as a solution to cope with this problem, by supporting more sophisticated communications among all the components, allowing the grid to react quickly to changes in both consumption or production of energy. On the other hand, resorting to information and communication technologies (ICT) brings some challenges, namely, managing network devices at this scale and assuring that the strict communication requirements are fulfilled is a dauting task. Software Defined Networks (SDN) can address some of these problems by separating the control and data planes, and logically centralizing network control in a controller. The centralised control has the ability to observe the current state of the network from a vantage point, and programatically react based on that view, making the management task substantially easier. In this thesis we provide a solution for a resilient communications network for Smart Grids based on SDN. As Smart Grids are very sensitive to network issues, such as latency and packet loss, it is important to detect and react to any fault in a timely manner. To achieve this we propose and develop two core modules, a network monitor and a routing and traffic engineering module. The first is a solution for monitoring with the goal to obtain a global view of the current state of the network. The solution is secure, allowing malicious attempts to subvert this module to be detected in a timely manner. This information is then used by the second module to make routing decisions. The routing and traffic engineering module ensures that the communications among the smart grid components are possible and fulfils the strict requirements of the Smart Grid

Collaborative transportation for small and medium enterprises for advancing the emerging countries

International audienceFood needs are growing rapidly with the growing population especially in case of developing countries where food preservation technology is not that much mature or even not available. It results enormous increase in prices of food commodities and higher growth rate of inflation each year. Additionally population is dispersed in the country in form of very small and large cities. Similarly, food grown in the country is also dispersed in the different areas of the country. This is highly necessary to use effective modes of transport, to collect food from these regions and distribute it with equilibrium in all the human living regions. Additionally to reduce the wastage of food in case of food shortage especially in some part of the African continent region. Food products and ingredients found and grown in one region are transported to another region, making it possible to use and eat them where they are not found. Small farmers or food producers to reach the scattered areas to distribute their products at time and cost effectively could not purchase their own vehicles, ships or planes to transport their goods. These companies contact third party transporter companies to transport their products, same as a courier company. These companies are called Third Party Logistics enterprises (3PL). These 3PL enterprises take the responsibility of performing logistics functions entirely or partially of an organization. They manage their own fleet of vehicles which drive in a certain and region. The diversity of clients due to different kind of product distribution (fresh, frozen etc.), distance from production companies and distribution cities, the size of the transport network make it even very complicated for a 3PL transporter to manage transportation planning and make efficient use of their resources. Moreover a single 3PL transporter also covers a limited region; they must collaborate with other 3PL enterprises which operate in other regions to make the delivery of the products to faraway locations. Complexity of transportation planning increases further in case of multiple 3PLE enterprises collaborating for the fulfilment of a transport order(s). The objective of this paper is to present a collaborative and distributed model for transportation planning activities aimed at better utilize transport resources by grouping several orders of transports for each effective displacement

Commercial Helicopter Services: Toward Quantitative Solutions for Understanding Industry Phenomena and Achieving Stakeholder Optimization

An understanding of industry phenomena and optimization techniques within the upstream energy industry’s transportation sector is markedly absent in the extant literature and suitable for rigorous investigation. This manuscript presents analyses related to the optimization of offshore worker transportation and econometric analyses of factors influencing commercial helicopter operators’ stock returns, which are represented throughout the manuscript as Part I and Part II, respectively. The global energy industry transports supplies and personnel via helicopter to offshore locations and has been increasingly focusing on optimizing upstream logistics. Using a unique sample of deepwater and ultra-deepwater permanent offshore locations in the Gulf of Mexico, transportation networks consisting of 58 locations operated by 19 firms are optimized via a randomized greedy algorithm. The model developed in Part I has been found to effectively solve the complex transportation problem and simulation results show the potential advantages of alternative clustered and integrated network structures, as compared to an independent firm-level structure. The evaluation of clustered and integrated network structures, which allow ride sharing via energy firm cooperation, provides evidence that such network structures may yield cost reductions for participating firms. The extent to which commercial helicopter operators’ stock returns are related to commodity prices and other relevant industry variables is absent in the extant literature. Often, firms attribute favorable results to internal factors whereas unfavorable results are attributed to external factors. Using a unique data set from 2013-2018, the current research identifies structural relationships between crude oil prices, natural gas prices, the rotary rig count, a subset of the overall market, firms’ degree of diversification and stock returns of commercial helicopter operators. Empirical analyses developed in Part II show that the prevalent price of crude oil and the overall market environment possess explanatory power of commercial helicopter firms’ stock returns, ceteris paribus. Specifically, 10% increases in the crude oil price and the S&P 500 index yield a 2.7% and 8.0% increase in stock returns, respectively. Collectively, the abovementioned parts of this manuscript provide rigorous, quantitative analyses of topics unrepresented within the extant literature, which are foundational for future practice and research. Specifically, new knowledge regarding a practical approach to model development and solution deliverance for the transportation of offshore workers to their respective locations and factors influencing commercial helicopter operators’ stock returns has been appropriately designed and empirically evaluated